Question

Find the sum of all natural numbers between 200and 500 which is divisible by 3

Answer 1

Hey friend,


First term b/w 200 and 500=>201 (A1)
which is divisible by 3.

Last term b/w 200 and 500=>498(An)
which is divisible by 3

Difference b/w the terms=3(d)


So, First we find Total no. between 200 and 500 which are divisible by 3.

By formula=> An=A1+(n-1)×d

=>498 = 201+(n-1)×3
=>498 = 201+3n-3

Dividing Both side by 3

=>166 = 67+n-1
=>166 = 66+n
=>100 = n


So, the no. of terms are 100

Now,we find Sum of all 100 terms

By formula=>Sn= n/2 [A1+An]

=>Sn = 100/2 [201+498]
=>Sn = 50×699
=>Sn = 3495

So, the sum of all natural numbers between 200 and 500 which are divisible by 3 => 3495.



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