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Number Systems -Sequence and Series

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by theCodeToGMAT » Thu Oct 17, 2013 8:48 am
Sum of series till 44 - Sum of series till 35

using formula : (N)(N+1)(2N+1)/6

(44)(45)(89)/6 - (35)(36)(71)/6

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by sanjoy18 » Thu Oct 17, 2013 12:44 pm
just calculate the last two digit of each term and then add it will give last two digit of final result which is 60 hence C

to calculate last two digit easily.
last two digit of x^2= last two digit of(50-x)^2

example: last two digit of 36^2= last two digit of 14^2 i.g. 96[/b]
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