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:
18 comments Page 2 of 2.
Anomie said:
1 year ago
50 * 50 + (1+2+3...50)
= 2500 + 50/2(1+50).
= 2500 + 25 * 51.
= 2500 + 1275.
= 3775.
= 2500 + 50/2(1+50).
= 2500 + 25 * 51.
= 2500 + 1275.
= 3775.
Tanisha Rajak said:
4 years ago
Thanks guys for explaining this.
Janardhan jada said:
4 years ago
Thanks to all for explaining the answer.
Rupam Bhattacharjee said:
1 decade 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
NP said:
7 years ago
Here, n is number of turns
this ex. is (51 to 100 then n is 50 number).
this ex. is (51 to 100 then n is 50 number).
Pooja said:
1 decade ago
n/2[firstnum + lastnum].
n = 50{totalnum}.
50/2[50+100].
= 25[151].
= 3775.
n = 50{totalnum}.
50/2[50+100].
= 25[151].
= 3775.
Rajkin hossain said:
1 decade ago
Look my friends
51+100=151
52+99=151
53+97=151
If we are following in that way then we have 25 times 151
So the ans is 25*151=3775.
51+100=151
52+99=151
53+97=151
If we are following in that way then we have 25 times 151
So the ans is 25*151=3775.
Tanya Mazumdar said:
1 decade ago
Thanks for the right and easiest technique.
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