Question

Find the sum of all natural numbers which are less than 500 and also which are multiply of 7

Answer 1

Answer:

But some digits divisible by 7 are also divisible by 11 in an arithmetic progression of 77, 144, 221, 298…… 462 and it it's necessary to find the number of numbers in this series.

Answer 2

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The sum of all natural numbers which are less than 500 and also which are multiple of 7

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Natural number less than 500 and are multiple of 7 is :

7, 14, 21, ... , 497

Here,

a = 7

d = 7

{Last Term = 497}

l = a + (n-1)d

497 = 7 + (n-1)7

497 - 7 = (n-1) 7

490/7 = (n-1)

70 = (n-1)

n = 70 + 1

n = 71

Hence, there are total 71 terms.

SUM:

71/2 (7 + 497)

71/2 (504)

71(252)

17,892

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