expression for the sum of 1 thru 20

[MeghannDawkins]

I need a generic expression to find the sum of a group of numbers like 1 thru 20 using this set up ( )( )/( ).

 

[mmm4444bot]

The formula for the sum of the first n Natural numbers is:

1 + 2 + 3 + … + n = n(n + 1)/2

Using your example of the sum of the first 20 Natural numbers, I guess your ()()/() setup would be (20)(21)/(2).

 

[MeghannDawkins]

Thanks you're the best. It's been a long time since I've done this stuff. Trying to help my son :wink: