Help with Percentages

[billyshears]

I am trying to do this in excel but I need to understand the math first.

Lets say I have the number 100. I want to find a number that when added to 100, will equal 10% of 100+new number.

For instance, if I added 11.1111 to 100, 11.1111 would be 10% of 111.1111.

How do I do that mathematically?

 

[stapel]

I am trying to do this in excel but I need to understand the math first.

Lets say I have the number 100. I want to find a number that when added to 100, will equal 10% of 100+new number.

For instance, if I added 11.1111 to 100, 11.1111 would be 10% of 111.1111.

How do I do that mathematically?

To do it mathematically, you'd start by translating!

You're trying to find "a number", so name this unknown: n

You are going to be adding this number to 100: 100 + n

You want this number also to be ten percent of the new number, so: n = 0.10(100 + n)

Expand the right-hand side, and solve the resulting linear equation.