TestMagic Forums - View Single Post - Sum of even numbers:-

NishantG · 07-24-2008, 07:18 AM

Absolutely agree that the value of n should be 159

Error done by retake and others is that number of even numbers in the series should be (n-1)/2 and not n

So if you substitute this value in formula

Sum of AP = n/2(2*1st number + (n-1)d)

Here n=(n-1)/2 and d= 2

So sum of even numbers between 1 to n is (n-1)(n+1)/4

Using this formula value of n is 159

07-24-2008, 07:18 AM	#11 (permalink)
NishantG Within my grasp! Join Date: May 2008 Posts: 347	Absolutely agree that the value of n should be 159 Error done by retake and others is that number of even numbers in the series should be (n-1)/2 and not n So if you substitute this value in formula Sum of AP = n/2(2*1st number + (n-1)d) Here n=(n-1)/2 and d= 2 So sum of even numbers between 1 to n is (n-1)(n+1)/4 Using this formula value of n is 159