Find the sum of all natural numbers from 1 to 100 which are divisible

1.	Find the sum of all natural numbers from 1 to 100 which are divisible by 2 or 5
Answer» 2 will divide the numbers:2, 4, 6, 8, 10, 12…98, 100it will cover the multiples of 10 which will also be divisible by 5.so for 5 the remaining divisible numbers are:5, 15, 25, …85, 95both the sequences are A.P whose sum are = 50/2(2 + 100) = 2550 and 10/2(5 + 95) = 500 so total sum is 3050

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