The sum of first 45 natural numbers is:

Question

Accepted Answer

Let S n =(1 + 2 + 3 + ... + 45). This is an A.P. in which a =1, d =1, n = 45. Sn = n [2a + (n - 1)d] = 45 x [2 x 1 + (45 - 1) x 1] = ❨ 45 x 46 ❩ = (45 x 23) 2 2 2 = 45 x (20 + 3) = 45 x 20 + 45 x 3 = 900 + 135 = 1035. Shorcut Method: Sn = n(n + 1) =…

The sum of first 45 natural numbers is:

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Discussion & Comments

S_n =	n	[2a + (n - 1)d]	=	45	x [2 x 1 + (45 - 1) x 1]	=	❨	45	x 46	❩	= (45 x 23)
	2			2				2