Math CentralQuandaries & Queries


Question from Michael, a student:
I'm in 4th grade and need to express decimals as a fraction in its simplest form. Is there a step by step method to figure out? ex 0.64 = 64/100 = ?


All that is left is to put it into lowest terms. To do that, divide both the top and bottom by any "common factor" (number bigger than 1 that divides both of them) and keep going till they don't have a common factor any more.

Usually you have to try a lot of things for this but with percents it is easy because 100 is only divisible by 2, 5, and numbers you get by multiplying 2 and 5. So you don't have to try 7s and 13s and so on.

So: 38/100 = 19/50 and neither 2 or 5 divides 19. STOP.

35/100 = 7/20 and neither 2 nor 5 divides 7. STOP.
8/100 = 4/50 = 2/25. 5 doesn't divide 2, 2 doesn't divide 25. STOP.

Good Hunting!

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