Question

# Which of the following is not a triangular number?

A
1
B
3
C
6
D
11

Solution

## The correct option is C 11Triangular numbers are obtained by adding consecutive natural numbers. Now,  1=1 3=1+2 6=1+2+3 But 11(=1+2+3+5) can not be expressed in such a way. Hence, it is not a triangular number.

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