In Pickering I was browsing a second-hand bookshop / toy shop and came across the most unlikely of books to buy – Oxford Study Mathematics Dictionary. At £3.99 it was a bit expensive for an obscure read, but what magic is contained within!

It’s a maths dictionary. ie All the maths words and phrases, with a simple definition. As I work my way through the entries I will post any interesting entries. For example *happy numbers* and *sad numbers.*

19, for example, is a happy number because you can square all its digits and add them together to make another number and by repeating this process eventually you get a result which is the number 1.

For example 19 -> 1 + 81 -> 82 -> 64 + 4 -> 68 -> 36 + 64 -> 100 -> 1 + 0 + 0 -> 1

If this process doesn’t eventually result in the number 1, then the number is said to be ‘sad’! The number 18 is an example of a *sad* number! Do the maths yourself!

See Wikipedia to blow your mind further.