Question

If a positive number n satisfy \(n\ \equiv \ 0 \ mod(2)\) and \(n\ \equiv \ 0 \ mod(5)\). Find the 2nd smallest possible value of n is 

Answer 1

Correct Answer - Option 2 : 20

Calculation:

\(n\ \equiv \ 0 \ mod(2)\)

\(n\ \equiv \ 0 \ mod(5)\)

That means we have to find n such that, when it is divided by 2 and 5, gives remainder 0. 

Hence, number n will satisfy

n = 2k and n = 5K

Therefore, the general solution is

n = 10K, where k = 1, 2, ....

Hence, the second smallest value will be at k = 2

⇒ n = 10 × 2 = 20

⇒ n = 20