11 + 12 + 13 + ... 51 + 52 + 53 = ? Choices: A) 1361 B) 1376 C) 1363 D) 1364 E) 1365
Sum = 11 + 12 + 13 + ... 51 + 52 + 53   Sum of n consecutive positive integers starting from 1 is given as n(n+1)/2   Sum of first 53 positive integers = 53*54/2   Sum of first 10 positive integers = 11*10/2   Sum = 11 + 12 + 13 + ... 51 + 52 + 53 = 53*54/2 - 11*10/2= 
<gadget id="calculator">53*54/2 - 11*10/2</gadget>
<output>1_376</output>
1376   Answer : 1376
<result>B</result>
11 + 12 + 13 + ... 51 + 52 + 53 = ?