The central limit theorem is pretty cool and is outlined here.
So
toss a coin 100 times
count 1 for each head and 0 for each tail
add these numbers up ->sum
now repeat all of the above say 200 times
the 200 sum values will be distributed normally
eg
Sum/ Number of occurrences
2 /…3
10 /…..5
15 /……..8
23 /…………12
32 /……………………23
41 /……………………………..35
52 /…………………………………………….50
65 /………………………..29
73 /……………15
75 /……….10
82 /….4
93 /….4
95 /.1
100 /.1
