• Numerical Ability - Number System
Question

The sum of integers from 113 to 113113 which are divisible by 7 is :

  • A) 92358576
  • B) 913952088 
  • C) 94501895 
  • D) 912952066 
  • E) None of these
Solution

Ans.2

Since 913952088 is divisible by 7

Alternatively: a = 119
a + d = 119 + 7 = 126
a + 2d = 119 + 14 = 133
So, the numbers which are divisible by 7 are 119, 126, 133 …. 113113 ….
So, number of terms = [113113 ? 119/7] + 1 = 16143
S16143 = [ 119 + 113113 /2 ] × 16143 = 913952088
Hint: The unit digit will be 8 as [9+3/2] × 3
6 × 3 = 8
Hence, only choice (b) is appropriate.

Ans.2

Since 913952088 is divisible by 7

Alternatively: a = 119
a + d = 119 + 7 = 126
a + 2d = 119 + 14 = 133
So, the numbers which are divisible by 7 are 119, 126, 133 …. 113113 ….
So, number of terms = [113113 ? 119/7] + 1 = 16143
S16143 = [ 119 + 113113 /2 ] × 16143 = 913952088
Hint: The unit digit will be 8 as [9+3/2] × 3
6 × 3 = 8
Hence, only choice (b) is appropriate.
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