Question

find the sum of all multiples of 7 lying between 300 and 700

Answer 1

Hii friend,

Multiple of 7 which lying between 300 to 700 are 301,308, 315,..........,700.

Here,

A = 301

D = 7

Tn = 700

a+(n-1) × d = 700

301 + (n-1) × 7 = 700

301 + 7n - 7 = 700

7n = 700-294

7n = 406

n = 406/7

n = 58

Therefore,

Sn = n/2 × [ 2a + (n-1) × d]

Sn = 58/2 × [ 2 × 301 + (58-1) × 7 ]

= 29 × 602 + 399

= 17458 + 399 = 17857 .

Hence,

The sum of the number which is divisible by 7 between 300 and 700 is 17857 .

HOPE IT WILL HELP YOU.... :-)

Answer 2

Answer:

17857

Step-by-step explanation:

see attachment

first step in second pic

PLZZ.. mark it as brainliest

:) hope this helps you mate (: