Question

Program to find sum of all integers between 100 to 9000 and are divisible by 7 in c

Answer 1

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Here is ur answer

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Answer 2

Answer:

5783050

Step-by-step explanation:

Since, integers between 100 to 9000 that are divisible by 7,

105, 112, 119, .......... 8995,

Which is an AP,

Having first term, a = 105,

d = 7,

Last term, l = 8995

Let n be the total number of terms,

$\implies a + (n-1)d = l$

$105 + (n - 1)7 = 8995$

$7(n-1) = 8890$

$n - 1 = 1270$

$\implies n = 1271$

Hence, the sum of the above AP,

$S_{1271}=\frac{1271}{2}(2(105)+(1271-1)7)$

$=\frac{1271}{2}(210+1270(7))$

$=\frac{1271}{2}(9100)$

$=1271\times 4550$

= 5783050

Hence, the sum of all integers between 100 to 9000 and are divisible by 7  is 5783050.