Question

find the sum of all multiples of 3
lying between 250 and 1000​

Answer 1

Answer:

the number between 250 and 1000 which are divisible by 3 are 252 , 255,258,....999

this is an A. P. whose first term a = 252. common difference between, d=3 and last term I =999

we know that

I =a+(n-1) d

999=252+(n-1)

n=250

we know that

S = n/2(a+I)

=250/2(252+999)

= 125*1251

= 156375

Hence, the required sum is 156375 . (ans)

I hope it's help you