Why are decimals used in money?

Answer 1

Basically because people have ten fingers. Humans understand base ten and are more familiar with it than other number bases. This hasn't always been the case though. In my country England, we used the base 12 system of pounds shillings and denari up until 1972. I learned the times tables up to the 12 times table specifically for the purpose of being comfortable with that number base.

Why did England use base 12? Well that was a left over from the Roman period. You see the Romans used base 12 because it was easily divisible by many other numbers which made dividing equal shares in money easier. So for them it actually had purpose.

Another reason for base 10 is simplicity of numbers. If i have 100 pennies in base ten...

... but I use binary to write it down it would be the binary number 1100100 !

Can you imagine going into a shop and asking for "one, one, oh, oh, one,oh,oh's" worth of sweets?

You could go the other way and use a larger base number like base 16, and on paper our 100 pennies becomes 64 hex, a much smaller number, but then you would have to teach everyone how to perform mathematics in base sixteen. If they wanted to use their fingers to do the addition in base 16 you would also need to get them to grow another six fingers or use their toes.

I don't know about you but the thought of a class of school children in a maths class with their socks off turns my stomach, and would probably result in less healthy teachers