What number would replace the question mark (?) in the series given below? 1, 3, 6, 10, 15, 21, ?, 36

A32

B28 ✓ Correct

C29

D30

Correct answer: (B) 28

Explanation

The missing term is 28.

These are triangular numbers, each adding the next integer.

21 + 7 = 28.

Check: 28 + 8 = 36 matches the last term.

So the term is 28.

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