The document contains code for multiple Android activities that calculate various mathematical operations and conversions by taking user input from edit texts, performing calculations, and displaying outputs in text views. The activities include subtraction of 3 numbers, perimeter calculations for polygons, unit conversions between meters to centimeters, etc. The code follows a similar structure for each activity of getting references to edit texts and text views, parsing user input, performing calculations, and setting the text view to the output.

1. Package com.example. Resta de 3 números
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
}
Publicvoid restar(viewview){
EditText et1=(EditText) findViewById(R.id.num1);
EditText et2=(EditText) findViewById(R.id.num2);
EditText et3=(EditText) findViewById(R.id.num3);

2. TextView et4=(TextView) findViewById(R.id.tv3);
Double
n1=Double.parseDouble (et1.getText().toString());
Double
n2=Double.parseDouble (et2.getText().toString());
Double
n3=Double.parseDouble (et3.getText().toString());
double r;
r=n1-n2-n3;
et4.setText(String.valueOf)(“El resultadode “+n1+”-“+n2+”-“+n3+”=”r));
}
Package com.example. perímetro de un hexágono
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}

3. Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r=n1 *6;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”r));
}
Package com.example. perímetro de un octagono
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);

4. Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *5;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”r));
}
Package com.example. perímetro de un nonágono
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override

5. Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById (R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *7;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. metros a cm
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{

6. Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *100;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. m a mm
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;

7. Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *2000;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. Metros a pulgadas
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;

8. Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *37.23;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. metros a pies
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;

9. Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *3.28;
sol.setText(String.valueOf)(“El resultadode “+n2+”=”+r));
}
Package com.example. Hora a minutos
Import andrioid.os.Bundle;
Importandroid.app.Activity;

10. Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *20;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. Kilogramos a gramos
Import andrioid.os.Bundle;

11. Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *1000g;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. Toneladas a kilogramos

12. Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *1000;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));

13. }
Package com.example. yardas a centimetros
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *91.44;

14. sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. millas a pres
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById (R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double r;

15. r= n1 *5367;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
}
Package com.example. Minutos a segundos
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());

16. Double r;
r= n1 *60;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
Package com.example. horas a segundos
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
TextView sol=(TextView) findViewById(R.id.res);

17. Double
n1=Double.parseDouble (num1.getText().toString());
Double r;
r= n1 *3600;
sol.setText(String.valueOf)(“El resultadode “+n1+”=”+r));
Package com.example. suma de dos numerous elavado al cuadrado
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){

18. EditText num1=(EditText) findViewById(R.id.et1);
EditText num2=(EditText) findViewById(R.id.et2);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double
n2=Double.parseDouble (num2.getText().toString());
Double r;
r= (n1+n2)+(n2+n2);
sol.setText(String.valueOf)(“El resultadode “+n1+”+”+n2”=+r));
}
Package com.example. sustracciónde 3 números
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override

19. PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText num1=(EditText) findViewById(R.id.et1);
EditText num2=(EditText) findViewById(R.id.et2);
EditText num3=(EditText) findViewById(R.id.et3);
TextView sol=(TextView) findViewById(R.id.res);
Double
n1=Double.parseDouble (num1.getText().toString());
Double
n2=Double.parseDouble (num2.getText().toString());
Double
n3=Double.parseDouble (num3.getText().toString());
Double r;
r= n1-n2-n3
sol.setText(String.valueOf)(“El resultadode “+n1”-“+n2+”-“n3+”=+r));
}
Package com.example. apotemade circulo
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;

20. Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText lado=(EditText) findViewById(R.id.et1);
EditText apotema=(EditText) findViewById(R.id.et2);
EditText res=(EditText)findViewById(R.id.res);
Double
lad=Double.parseDouble (num1.getText().toString());
Double
apotem=Double.parseDouble(num2.getText().toString());
Double
Area;
Area=((9*lado)*apotem/2;
Res.setText(string.valueoF(area)) }

21. Package com.example. áreade un cuadrado
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText et1=(EditText) findViewById(R.id.et1);
EditText et2=(EditText) findViewById(R.id.et2);
TextView sol=(TextView) findViewById(R.id.res);
Double
nro1=Double.parseDouble (et1.getText().toString());
Double
nro2=Double.parseDouble (et2.getText().toString());

22. Double r;
r= nro1-nro2;
sol.setText(String.valueOf)(“El resultadode “+nro1”*“+nro2+”-”=+r));
}
Package com.example. volumende una piramide
Import andrioid.os.Bundle;
Importandroid.app.Activity;
Import android.view.Menu;
Import android.view.View;
Import android.widget.Edittext;
Import android.widget.Textview;
Publicclass MainActivity extends activity{
Override
Protectedvoid oncreate(BundLe savedInstanceState){
Super.oncreate(savedInstanceState);
Setcontenview(R.layout.activity_mauin);
}
Override
PublicBoolean oncreateOptionsMenu(MenuMenu){
// Inflate the menu;thisaddsitemstothe actionbar if is present.
getMenuInflater().inflater(R.menu.main,menu);
returntrue;
Publicvoid Calcular(viewview){
EditText et1=(EditText) findViewById(R.id.EditText1);
EditText et2=(EditText) findViewById (R.id.EditText2);
EditText et3=( EditText) findViewById(R.id. EditText3);

23. int
nro1=Integer.parseInt(et1.getText().toString());
int
nro2=Integer.parseInt(et2.getText().toString());
intres=nro1*nro2/3;
et3setText(String.valueOf(res));
}