Question

Find the sum of all 3 digit multiples of 7​

Answer 1

Answer:

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Step-by-step explanation:

Smallest 3 digit no. divisible by 7=

105 and the largest =994

An=105

D=7

n =?

An = A +(n-1)D

thus

994=105+(n-1)7

thus by solving further

n = 128

now ,

Sn = n/2[A+An]

Sn =128/2[105+994]

thus,

Sn =770336

Thus the sum of all the 3 digit numbers divisible by 7= 770336

Answer 2

Answer:

So , number of 3 digit numbers divisible by 7 is 128. Substitute 1.=105 by Q=7, 2.994 by Q=128.So,the sum of all 3 digit numbers divisible by 7 is 70336.

Step-by-step explanation:

Shortcut

First divide 7 by 100 . The remainder will be 2.

Step 1 = Subtract 2 from 7 . 7-2=5

Step 2= Add the result 5 to 100 . 100+5=105.

105 is the first 3 digit number divisible by 7 .

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