Multiplying rational numbers

For part 2 of https://trello.com/c/EqP0nOuH/164-four-operations-with-rational-numbers

Some of the questions are quite nasty (i.e. a lot of calculation), especially multiplying repeated numbers. I suppose I could include a calculator for those questions.

Also updated the graphie Multiplier so when the second number is <1, it doesn't bother multiplying all the digits in the first number by the leading zero. However, for numbers < 0.1, it will still multiply by any zero after the decimal point (I'll see if I can fix this).