How to find the value of y in a fraction

Answer 1

I'm going to try to infer a lot here, because the question is so obscure. I assume you're being asked to work out what the denominator of a fraction is when you're presented with the equivalent decimal. So suppose you're given a decimal number like 0.42, and you're asked to express it as a simple fraction x/y in the simplest possible terms. If that's right, the first thing to do is express it as ANY fraction - and the most obvious one in this example would be 42/100. Now try to reduce it to its simplest form - and you do that by finding factors that are common to both the numerator and the denominator. The numerator factorizes as (7 x 6) = (7 x 3 x 2), whereas the denominator is (2 x 2 x 5 x 5). Of these, only a single 2 is common to both the numerator and the denominator, so the best you can do is reduce the fraction to (21/50). Does that help, or are you trying to do something else entirely?