Monday, 9 March 2015

Sum of n consecutive numbers











Is there a shortcut method to working out the sum of n consecutive positive integers?



Firstly, starting at 1...1+2+3+4+5=15.



Secondly, starting at any other positive integer ...(10 e.g.): 10+11+12+13=46.


Answer



Take the average of the first number and the last number, and multiply by the number of numbers.


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