12 + 13 + 14 + ... 51 + 52 + 53+ 54 = ?
Choose the correct choice.
A) 1419  B) 1362  C) 1363  D) 1364  E) 1365
Sum = 12 + 13 + 14 + ... 51 + 52 + 53 + 54   Sum of n consecutive positive integers starting from 1 is given as n(n+1)/2   Sum of first 54 positive integers = 55*54/2   Sum of first 11 positive integers = 11*12/2   Sum = 12 + 13 + 14 + ... 51 + 52 + 53 + 54 = 55*54/2 - 11*12/2= 
<gadget id="calculator">55*54/2 - 11*12/2</gadget>
<output>1_419</output>
1419   1419nswer : 1419
<result>A</result>
12 + 13 + 14 + ... 51 + 52 + 53+ 54 = ?