avoid two digits repeating decimal with same number

like *1.**22***
example: [adding_and_subtracting_rational_numbers.html?seed=69&problem=repeating-decimals](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/adding_and_subtracting_rational_numbers.html?seed=69&problem=repeating-decimals&debug)
suggestion from spicyj
Merge pull request #59452 from mauk81/patch-1

avoid two digits repeating decimal with same number