Q24 of 52 Page 1

Find the sum of all multiples of 8 lying between 201 and 950.

To find: 208 + 216 + 224 + …….. + 944


Given,


a = 208,


d = 216 – 208 = 8


an = 944


a + (n – 1)d = an


Therefore,


208 + (n-1) 8 = 944


(n-1)8 = 944 – 208 = 736


n – 1 = 736/8 = 92


n = 92 + 1 = 93


Sn = n/2(a1 + a2)


S93 = 93/2 (208+944)


= 93/2×1152 = 93×576 = 53568


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