Find the sum of all multiples of 7 between 500 and 800
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The list of numbers between 500 and 800 that are multiples of 7 is :
504, 511, 518,.........................798.
Clearly the above list is in AP with first term, a = 504 and common difference, d = 7.
Let the nth term of AP is 798.
an = a + (n - 1)d
⇒ 798 = 504 + (n - 1)(7)
⇒ n = 43
sum of first 43 terms of the above AP is given by,
504, 511, 518,.........................798.
Clearly the above list is in AP with first term, a = 504 and common difference, d = 7.
Let the nth term of AP is 798.
an = a + (n - 1)d
⇒ 798 = 504 + (n - 1)(7)
⇒ n = 43
sum of first 43 terms of the above AP is given by,
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