5thtriangularnumber

<-- Enter triangular number statement
  

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Calculate triangular number 5

The formula for triangular number n is as follows

Tn  =	n(n + 1)
	2

Given n = 5, we have:

T5  =	5(5 + 1)
	2

T5  =	5(6)
	2

T5  =	30
	2

T₅ = 15

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