I would use the elimination method by dividing them by prime numbers:
First of all, 360 and 500 are not divisible by 7, so we can already rule out C and E.
500 is not divisible by 15, so we can rule out B.
All three numbers are divisible by both 4 (2 would be the prime number) and 5, and since 4 and 5 are larger factors than 2 and 5 (as in option A) we know the answer must be D.
Does this help? :))
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I thought I had to do the finding common multiple methods but I guess my wrong was not realizing the prime number wording.
thank you!
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Well technically you could I think but it would take longer than eliminating the answers I believe. But if anyone has an alternate method please share it!!
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Hey! I think the easiest way of solving this is by decomposing each number into their prime factors (and using the following shortcut to save time):
360= 36x10 = 6×6×5×2=3×2 × 3×2 x 5x2
500= 5×100 = 5×10×10=5×5×2×5×2
700=7×100=7×10×10=7×5×2×5×2
So the HCF of this 3 numbers would be: 2x2x5
Hope this helps!
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Ooo I love this technique Aizza, thank you so much!! 
definitely seems faster
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