Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 88)
88.
(51+ 52 + 53 + ... + 100) = ?
Answer: Option
Explanation:
This is an A.P. in which a = 51, l = 100 and n = 50.
 Sum = |
n | (a + l) | = | 50 | x (51 + 100) = (25 x 151) = 3775. |
| 2 | 2 |
Discussion:
6 comments Page 1 of 1.
Veer said:
1 year ago
Please explain to me in detail.
Blaise M said:
2 years ago
a(first term) = 51,
l(last term)=100,
N(no of terms)= 50 ie..51-100.
We use the formula:
= n/2(a+l).
= 50/2(51+100),
= 25*151,
= 3775.
l(last term)=100,
N(no of terms)= 50 ie..51-100.
We use the formula:
= n/2(a+l).
= 50/2(51+100),
= 25*151,
= 3775.
(1)
Koushik said:
5 years ago
Sum of first n natural numbers is n(n+1)/2.
Now, we can find this answer by = (sum of n natural numbers between 1 to 100) - (sum of n natural numbers between 1 to 50).
So [100* (100+1)/2] - [50 * (50+1)/2],
=5050 - 1275,
= 3775.
Now, we can find this answer by = (sum of n natural numbers between 1 to 100) - (sum of n natural numbers between 1 to 50).
So [100* (100+1)/2] - [50 * (50+1)/2],
=5050 - 1275,
= 3775.
(2)
Shahbaj said:
5 years ago
@Donkupar Lynnong.
Arithmetic Progression.
Arithmetic Progression.
DONKUPAR LYNNONG said:
6 years ago
What is the full form of A. P? Please tell me.
(1)
Divya said:
9 years ago
N(N + 1)/2 by using this formula we get, 100(101)/2 = 50 * 101,
= 5050 - 50(51)/2,
= 5050 - 1275 = 3775.
= 5050 - 50(51)/2,
= 5050 - 1275 = 3775.
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