Question

Find the sum of all two digit number divisible by 2​

Answer 1

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AP = 10 , 12 , 14 , ........98

a = 10 , d = 2 An = 98

An = a + (n-1)d

98 = 10 + (n-1)2

98 -10 = (n-1)2

88/2 = n-1

44 = n-1

n = 45

Sum of 45 Terms = n/2 (a + An)

= 45/2 (10 +98)

= 45/2 × 108

= 45 × 54

= 2430

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