find the sum of natural no's between 200 and 400 which is exactly divisible by 7
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Heya user,
Basically , if we interpret the question,
we've got to find the sum :->
[ 203 + 210 + ... + 399 ] = 7 [ 29 + 30 + ... + 57 ]
= 7 [ 1 + 2 + ... + 57 - [ 1 + 2 + .... + 28 ] ]
= 7 [ 29 * 57 - 14 * 29 ] = 7 * 29 * 43 = 8729 <--- Ans.
^__^ Enjoy the easiest method ... HEHE
Basically , if we interpret the question,
we've got to find the sum :->
[ 203 + 210 + ... + 399 ] = 7 [ 29 + 30 + ... + 57 ]
= 7 [ 1 + 2 + ... + 57 - [ 1 + 2 + .... + 28 ] ]
= 7 [ 29 * 57 - 14 * 29 ] = 7 * 29 * 43 = 8729 <--- Ans.
^__^ Enjoy the easiest method ... HEHE
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