Maths........

1+2-3+4-5...........97+98-99+100=?
Method 1:
Use a pen/pencil and some pieces of paper, add the numbers one by one.
Method 2:
Use a calculator, add the numbers one by one.
Method 3 (by calculation):
Given total numbers = 100
Divide the numbers into 50 pairs.
We can find that the sum of the first (smallest) and the last (largest) number = (1 + 100) = 101
Similarly, the sum of the second pair (second and the second largest) = (2 + 99) = 101,
And so do the rest of the 50 pairs………
Therefore,
Sum of (1+2-3+4-5...........97+98-99+100) is
101 * 50 = 5050 (ans.)


Hope can help you.