Question

Find the sum of all multiples of 7 lying between 103 and 999.

Please solve this question :

Answer 1

multiples of 7 lying between 103 and 999
are 105,112,119.............994
AP= 105,112,119.............994
a=105,d=112-105=7
nth term=994
nth term= a+(n-1)d
994= 105+(n-1)7
994-105=(n-1)7
889=(n-1)7
n-1= 889/7
n-1=127
n=128


n=128

sum of all 128 terms
=n/2(a+nth term)
=128/2(105+994)
=128/2(1099)
=64*1099
=70336

Sum of all the multiples of 7 between 103 and 994 is 70336

PLEASE MARK IT AS BRAINLIEST

Answer 2

here is your solution