On simplification, 1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 +  _____+ 111, we get

Correct option is C

Given:

1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 + ......... + 111

Solution:

Group the terms in pairs:

(1 - 2) + (3 - 4) + (5 - 6) + ........ + (109 - 110) + 111

Each pair equals:

(2k-1) - (2k) = -1

Number of terms = 111

First 110 terms form ( $$\frac{110}{2}$$​ = 55 ) pairs

Sum of pairs:

55 × (-1) = -55

Add the last unpaired term:

-55 + 111 = 56

Alternate Solution (Exam Trick):

In alternating sums ending with an odd number of terms,

Result = $$\text{Last term} - \frac{(\text{Last term} - 1)}{2}$$​​

= 111 - 55 = 56