BTGmoderatorDC wrote:If N is a positive integer, what is the tens digit of N?
(1) N is divisible by 25.
(2) N is divisible by 16.
OA C
Source: Veritas Prep
Let's take each statement one by one.
(1) N is divisible by 25.
1. Say N = 25, tens digit of N = 2.
2. Say N = 50, tens digit of N = 5.
No unique answer. Insufficient.
(2) N is divisible by 16.
1. Say N = 16, tens digit of N = 1.
2. Say N = 32, tens digit of N = 3.
No unique answer. Insufficient.
(1) and (2) together
Since 25 and 16 are co-prime, we conclude that N is divisible by 25*16 = 400.
Say N = 400k, where k is any positive integer
Whatever be the value of k, the tens digit of 400k would be 0. Sufficient.
The correct answer:
C
Hope this helps!
-Jay
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