Find the sum of natural numbers lying between 1 to 1000 which are divisible by 3.

Asked by ashleshathakur124 | 10th Feb, 2020, 09:46: PM

Expert Answer:

 
Here, 
 
3, 6, 9,   .....  999 are the natural numbers between 1 to 1000 which are divisible by 3 and this is an A.P.

 
a = 3, d = 3 and an = 999
 
We know that, 
 
an = a + (n - 1)d
→ 999 = 3 + (n - 1)3
→ 3(n-1) = 996
→ n = 333
 
Sn = n/2(a + l) = 333/2(3 + 999) = (333/2)×1002 = 166833

Answered by Yasmeen Khan | 11th Feb, 2020, 11:40: AM