Instructions

What will come in place of the question mark (?) in the following number series ?

Question 90

101, 103, 109, 121, 141, ?

Solution

Numbers of the form $$n (n + 1)$$ are added, where n is natural number.

101 $$+ 1 \times 2$$ = 103

103 $$+ 2 \times 3$$ = 109

109 $$+ 3 \times 4$$ = 121

121 $$+ 4 \times 5$$ = 141

141 $$+ 5 \times 6$$ = 171

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