Question

Using AP, find the sum of all 3-digit natural numbers which are the multiples of 7.​

Answer 1

Answer:

answer is 70336

Step-by-step explanation:

A.P = 105,112,119........994

a=105     d=7        l=994

l=a+(n-1)d

994=105+(n-1)7

n=128

therefore,

sum = n/2(a+l)

=128/2(105+994)=70336

sum of all multiples of 7 = 70336