# Math Help - How quickly can you add numbers from zero to one hundred without using a calculator?

1. ## How quickly can you add numbers from zero to one hundred without using a calculator?

Question:
Suppose you have a list of numbers from zero to one hundred. How quickly can you add them all up without using a calculator?

Is there a simple way or a trick to add them quickly?

2. Yes, there is.

$\frac{n(n+1)}{2}$

Now, let n=100

$\frac{100(101)}{2}=5050$

3. Originally Posted by looi76
Suppose you have a list of numbers from zero to one hundred. How quickly can you add them all up without using a calculator?

Is there a simple way or a trick to add them quickly?
100 + 1 = ?
99 + 2 = ?
98 + 3 = ?
...
51 + 50 = ?

How many such pairs are there?

So what is the sum?