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Multiplication ppt

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Multiplication ppt

1. 1. MULTIPLICATION BY: ABHA ARORA
2. 2. <ul><li>12 can be breaked as </li></ul><ul><li>(10 + 2 ) </li></ul>
3. 3. Multiplication by breaking numbers 4 x 7
4. 4. Break 7 as (5 + 2)
5. 5. 4 x 2 = 8 4 x 5 = 20
6. 6. <ul><li>4 x 7 = 4 x (5 + 2) </li></ul><ul><ul><ul><ul><li> = 4 x 5 + 4 x2 </li></ul></ul></ul></ul><ul><ul><ul><ul><li> = 20 + 8 </li></ul></ul></ul></ul><ul><ul><ul><ul><li> = 28 </li></ul></ul></ul></ul>
7. 7. Lets take one more example <ul><li> 12 x 2 </li></ul>
8. 8. 10 x 2 = 20 2x 4 = 4
9. 9. <ul><li>( 10 + 2 ) x 2 = 10 x 2 + 2x 2 </li></ul><ul><ul><ul><ul><ul><li> = 20 + 4 </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>= 24 </li></ul></ul></ul></ul></ul>
10. 10. Find the product by breaking up a factor <ul><li>37 x 8 = ? </li></ul><ul><li>37 = ( 30 + 7 ) </li></ul><ul><li>37 x 8 = (30 x 8) + (7 x 8) </li></ul><ul><li> = 240 + 56 </li></ul><ul><li> = 296 </li></ul>
11. 11. <ul><li>B) 235 x 3 = ? </li></ul><ul><li>235 = 200 + 30 + 5 </li></ul><ul><li>235 x 3 = (200 x 3) + (30 x 3) + (5 x 3) </li></ul><ul><li> = 600 + 90 + 15 </li></ul><ul><li> = 705 </li></ul>
12. 12. <ul><li>146 x 8 </li></ul><ul><li>146 = 100 + 40 + 6 </li></ul><ul><li>146 x 8 = ( 100x8 ) + ( 40x8 ) + ( 6x8 ) </li></ul><ul><li> = 800 + 320 +48 </li></ul><ul><li> = 1168 </li></ul>
13. 13. Multiplying by doubling <ul><li>If we know the 2 times table then we can work out the 4 times table by doubling. </li></ul><ul><li>Example </li></ul><ul><ul><ul><li>8 x 2 = 16 then 8 x 4 = 32 </li></ul></ul></ul><ul><ul><ul><li>Here 4 is the double of 2 and 32 is the double of 16 </li></ul></ul></ul>
14. 14. Similar examples : <ul><li>If 1 x 8 = 8 then 1 x 16 = 16 </li></ul><ul><li>2 x 8 = 16 then 2 x 16 = 32 </li></ul><ul><ul><li>3 x 8 = 24 then 3 x 16 = 48 </li></ul></ul>
15. 15. ACTION TIME : <ul><li>Double the 6 times table to find the product of : </li></ul><ul><li>A) 7 x 12 =? </li></ul><ul><li>We know 7 x 6 = 42 , so 7 x 12 = ?? </li></ul>
16. 16. <ul><li>B) 3 x 12 = ? </li></ul><ul><li>3 x 6 = 18 , so 3 x 12 = ? </li></ul>
17. 17. <ul><li>C) 8 x 12 = ? </li></ul><ul><li>8 x 6 = 48 , </li></ul><ul><li>so 8 x 12 = 96 </li></ul>
18. 18. Using multiples of 10 to multiply other numbers 8 x 19 = ? 8 x 20 =160 - 8 1 5 2
19. 19. <ul><li>6 x 39 = ? </li></ul>6 x 40 = 240 - 6 234
20. 20. Use multiples of 10 to find these products : <ul><li>A) 8 x 29 </li></ul><ul><li>30 is nearest tens to 29 , so we will find the </li></ul><ul><li>8 x 30 = 240 </li></ul><ul><li>- 8 </li></ul><ul><li> 232 </li></ul>
21. 21. <ul><li>B) 9 x 49 = ? </li></ul><ul><li>9 x 50 = 4 5 0 </li></ul><ul><li>- 9 </li></ul><ul><li>4 4 1 </li></ul>
22. 22. <ul><li>C) 4 x 69 = ? </li></ul><ul><li>4 x 70 = 2 8 0 </li></ul><ul><li> - 7 </li></ul><ul><li> 2 7 3 </li></ul>
23. 23. THANK YOU