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Numerical Ability
Arithmetic
2. What is the sum of the squares of the first 20 natural numbers (1 to 20)?
a) 2870
b) 2000
c) 5650
d) 44100
Read Solution (Total 25)
-
- n(n+1)(2n+1)/6
20(21)(21)/6
=2870 - 9 years agoHelpfull: Yes(13) No(7)
- it will be option a. using the formula n*(n+1)*(2n+1)/6 => 20*21*41/6=2870
- 9 years agoHelpfull: Yes(9) No(1)
- The sum of squares in natural n is=n(n+1)(2n+1)/6
i,e=20*21*41/6
=2870
- 9 years agoHelpfull: Yes(2) No(0)
- use sum of squares Formula:n*(n+1)*(2n+1)/6
n=20,answer=2870 (option A) - 9 years agoHelpfull: Yes(1) No(1)
- n/6*(n+1)*(2n+1)=2870
- 9 years agoHelpfull: Yes(1) No(0)
- it will be option a. using the formula n*(n+1)*(2n+1)/6 => 20*21*41/6=2870
- 9 years agoHelpfull: Yes(0) No(0)
- Use this formula n*n+1*2*n+1/6
so ans is 2870 - 9 years agoHelpfull: Yes(0) No(0)
- sum=n(n+1)(2n+1)/6=2870
- 9 years agoHelpfull: Yes(0) No(1)
- 20(21)(21)/6=2870
- 9 years agoHelpfull: Yes(0) No(1)
- a sum of the squares formula n(n+1)(2n+1)/6
- 9 years agoHelpfull: Yes(0) No(0)
- n(n+1)(2n+1)/6
=20*21*41/6
=2870 - 9 years agoHelpfull: Yes(0) No(0)
- n(n+1)(2n+1)/6
- 9 years agoHelpfull: Yes(0) No(0)
- n(n+1)(2n+1)/6
20(20+1)(41)/6
=2870 - 9 years agoHelpfull: Yes(0) No(0)
- a...2870.........n(n+1)(2n+1)/6....
- 9 years agoHelpfull: Yes(0) No(0)
- sum of squares of first n natural number is n(n+1)(2n+1)/6
so n=20
if we substitute we'll get 2870 as ans - 9 years agoHelpfull: Yes(0) No(0)
- 1+10=55
11+20=155
55+155=210
210^2=44100 - 9 years agoHelpfull: Yes(0) No(1)
- 1/6*n*(n+1)*(2n+1)....20*21*41/6
- 9 years agoHelpfull: Yes(0) No(0)
- a..by using formula n(n+1)(2n+1)/6
- 9 years agoHelpfull: Yes(0) No(0)
- answer is 2870
- 9 years agoHelpfull: Yes(0) No(2)
- sum of squares of first n natural nos=(n(n+1)(2n+1))/6
so required sum=(20(20+1)(2*20+1))/6=2870 - 9 years agoHelpfull: Yes(0) No(0)
- Use the formula for the summation of squares of first n natural numbers: n(n+1)(2n+1)/6
On substituting the value of n as 20 in this case, we get the answer as 2870. - 8 years agoHelpfull: Yes(0) No(0)
- option a is the answer
sum of squares of 1st n natural numbers={n*(2n+1)*(n+1)}/6
={20*21*41}/6
=2870 - 7 years agoHelpfull: Yes(0) No(0)
- n(n+1)(2n+1)/6
20(21)(21)/6
=2870 - 6 years agoHelpfull: Yes(0) No(0)
- n(n+1)(2n+1)/6
20(21)(21)/6
=2870 - 6 years agoHelpfull: Yes(0) No(0)
- The sum of squares of n natural numbers is:=n*(n+1)*(2 n+1)/6
=>20*(20+1)*(2*20+1)/6
=>(20*21*41)/6
=2870 - 4 years agoHelpfull: Yes(0) No(0)
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