find the sum of natural no. which are multiple of 5 and 7 between 100 and 1000.
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Hii its tom85
35 + 70 +105+ 140 + .........+ 980
980 = 35 +( n - 1)35
980= 35(n)
n= 28
sn = 28/2 {70 + (27)35}
Sn = 14*35*28
sn = 13720
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