Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 62)
62.
(51 + 52 + 53 + ... + 100) = ?
Answer: Option
Explanation:
Sn = (1 + 2 + 3 + ... + 50 + 51 + 52 + ... + 100) - (1 + 2 + 3 + ... + 50)
| = | 100 | x (1 + 100) - | 50 | x (1 + 50) |
| 2 | 2 |
= (50 x 101) - (25 x 51)
= (5050 - 1275)
= 3775.
Discussion:
21 comments Page 3 of 3.
Rupam Bhattacharjee said:
2 decades ago
You guys also can do that.........
51+52+53+.......+100
50/2(51+100)
=25*151
=3775 rule is n/2(first term+last term)=sum
51+52+53+.......+100
50/2(51+100)
=25*151
=3775 rule is n/2(first term+last term)=sum
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