Question

*11. Find the value of the expression (-1)+2+(-3) + 4 + ... + (-99) + 100.
Solution

Answer 1

• Answer:

50

• Explanation:

(-1) + 2 + (-3) + 4 + ... + (-99) + 100 =

= 2 - 1 + 4 - 3 + .. + 100 - 99

= 1 + 1 + .. + 1

= 50×1

= 50

Answer 2

50.

Explanation:

Each pair of numbers add up to 1:

-1 + 2 = 1, -3 + 4 = 1 and so on

There are 50 of theses pairs so the value is 50.