Question 37
($$2^{25} + 2 ^{26}+ 2 ^{27}+ 2^{28}$$ ) is a multiple of which of the following numbers?
Solution
$$2^{25}+2^{26}+2^{27}+2^{28}$$
$$=2^{25}\left(1+2+2^2+2^3\right).$$
$$=2^{25}\left(1+2+4+8\right).$$
$$=2^{25}\times15.$$
So, it is divisible by 15 .
B is correct choice.
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