The document discusses binary numbers and how to convert between binary and decimal representations. It explains that binary uses only two digits, 0 and 1, and the place value of each digit determines its weight. To convert binary to decimal, you multiply each binary digit by its place value and sum the results. It provides examples of converting individual numbers between binary and decimal formats and describes how to perform the conversions using Excel functions like SUM(), INT(), and MOD().

2. The first computer was NOT a binary machine
.. but that was a mistake

3. Which is clearer?

4. Which is clearer?

5. Confident?

6. recursive
89635839
010011010

7. How binary works
Units (1s)
0
2s
1
4s
1
 Just two numbers, 0 and 1
8s
1
16s
1
32s
0
 Place matters
64s
1
128s
0
 To convert to decimal, just add them up!
0*128 + 1*64 + 0*32 + 1*16 + 1*8 + 1*4 + 1*2 + 0*1

8. Can you do it?
Decimal number 128 64 32 16 8 4 2 1
0 0 0 0 0 1 1 0
0 1 0 0 0 1 1 1
0 0 0 0 0 0 0 0
0 1 0 1 0 1 0 1
1 0 1 1 1 1 0 1
0 0 1 0 1 0 1 1
1 1 1 1 1 1 1 1

9. Can you do it the other way?
Decimal number 128 64 32 16 8 4 2 1
6
7
15
23
62
127
96

10. What’s the bottom of Excel?

11. Excel binary to decimal
 Use eight cells for the binary number
 Put the magic numbers below:
 128,64,32,16,8,4,2,1
 Multiply *
 Add the results =sum()
 Make it look good
 Can you do it the other way round?

12. Excel decimal to binary
 Use =div() to divide by two
 Keep doing it
 Use =mod() to find the remainder
 That gives you the binary digits
=int(/2) Decimal number here
=mod(,2)

13. Can you ….
 Write out a binary number?
 Convert binary to decimal?
 Convert decimal to binary?
 Use multiply in a spreadsheet?
 Drag-Copy in a spreadsheet?
 Use =SUM() in a spreadsheet?
 Use =INT() in a spreadsheet?
 Use =MOD() in a spreadsheet?