Question

What is summation notation?

Answer 1

Summation is a shorthand way for writing long additions.

Explanation:

Say you want to add all numbers up to and including 50.
Then you could write out:
`1+2+3+......+49+50`
(If you really write this out in full, it'll be a long line of numbers).

With this notation you would write:
`sum_(k=1)^50 k`
Meaning: sum up all the numbers `k` from `1to50`
The `Sigma`-(sigma)-sign is the Greek letter for `S` (sum).

Another example:
If you want to add all the squares from `1to10` you simply write:
`sum_(k=1)^10 k^2`
You see that this `Sigma`-thing is a very versatile tool.