Question

Find the sum of all natural numbers between 250 and
1000 which are exactly divisible by 4.
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Answer 1

Answer:

Clearly the number between 250 & 1000 which are 252,255,258............999

this is a A.P with first term a = 252 common different =3 and last term =999

let there be n terms in this A.P

then An=999

a+(n-1) d =999

252+(n-1)*3=999

n=250

required sum =Sn=n/2 ( a+ l )

250/2 ( 252 + 999) =156375