What is the units digit of x?

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What is the units digit of x?

by BTGmoderatorDC » Tue Dec 05, 2017 6:35 am
What is the units digit of x?

(1) \(\frac{x}{5^a2^b3^c}=k\), where k is an integer.

(2) a = 2, b = 3, and c = 4

Can some experts identify the correct statement?

OA C

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by DavidG@VeritasPrep » Tue Dec 05, 2017 7:57 am
lheiannie07 wrote:What is the units digit of x?

(1) \(\frac{x}{5^a2^b3^c}=k\), where k is an integer.

(2) a = 2, b = 3, and c = 4

Can some experts identify the correct statement?

OA C
Statement 1 -
If a = b = c = 0, then x = k, so x and k can be integer we want. Not sufficient.

Statement 2 -
Nothing about x; not sufficient

Together: If $$x/(5^2 * 2^3 * 3^4) = k $$, and k is an integer, then we know that x will have to be a multiple of 5^2 * 2^3 * 3^4. Any number that contains 2*5 as part of its prime factorization will be a multiple of 10, and thus end in 0. Because we know that x will end in 0, the statements together are sufficient. The answer is C
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