which of the following has a terminating decimal?
10/189
5/196
16/225
25/144
39/128
The answer is easy when you have enough time. I'm posting this not to ask for the answer but to ask what or how can i solve this in 2 minutes without a calculator? there has to be a short way for doing so and I need your help on how. so please explain with detail not only the process but the way to solve it quickly, what tricks are there to solve this in 2 minutes only?
How to solve this one quickly?
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Moved this post to Problem Solving forum.
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backsolving backsolving backsolving.
Notice - backsolve from E. Works for you more frequently then backsolving from A
You need to prime factorize numerator and denominator.
If denominator will consist of 2's or 5's - it is 100% terminating decimal.
E)
39/128=(13*3)/(13*2*2*2*2)==>(3/2*2*2*2) => terminating decimal.
Notice - backsolve from E. Works for you more frequently then backsolving from A
You need to prime factorize numerator and denominator.
If denominator will consist of 2's or 5's - it is 100% terminating decimal.
E)
39/128=(13*3)/(13*2*2*2*2)==>(3/2*2*2*2) => terminating decimal.
how is 128 divisible by 13?
I understand and agree with the statement that if denominators prime factors are 2 and 5 only, then it will be terminating, however, still not seeing how you reduced the fraction.
I understand and agree with the statement that if denominators prime factors are 2 and 5 only, then it will be terminating, however, still not seeing how you reduced the fraction.
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(a) First convert fractions to lowest terms. (b) Then look for any denominator whose factors contain only 2 and 5.
GMAT trap: giving fractions in not-lowest terms, thereby trapping folks who know only (b).
GMAT trap: giving fractions in not-lowest terms, thereby trapping folks who know only (b).