Question

Find the sum of all multiples of 3 line between 101 and 999

Answer 1

hiii...I have smthg to answer for ur question..hope it might help u....by the process of AM we find the sum of all the multiples of 3 between 101 and 999....
a=102
an= 999
d=3
an= a+ (n-1)d
999= 102+(n-1)3
999-102=3n-3
897= 3n-3
897+3=3n
900=3n
n=300....

sn= n/2(a+l)
300/2(102+999)
150(1101)
165150....the sum is 165150.....
hope it helps u a lot...thanks for the question ......
jai.hind....

Answer 2

101 is not multiple of 3 so
first term (a)=102
last term (L)= 999
difference(d)=3
so
last term(L) = a+(n-1)*d
999 = 102+(n-1)*3
999-102=(n-1)*3
897/3=n-1
299+1=n
n=300
we know
sum(s)= n/2(a+L)
= 300/2(102+999)
=150*1101
= 165150