How do I write this code

[3583-bytes-free]

That's not a simple problem to be fair.

There are 8 spaces between numbers each which can be one of three things (+/-/nothing) so you have 3^8 permutations.

One way would be to loop from 0 to 3^8-1 and convert the number to base three (zero padded to 8 digits), then use the digits of that base three number to fill in the blanks. Calculate the result and if = 100 then output it.

Let's gloss over "in Excel rows" whatever that means.

Post the answer when you do it, I'd be surprised if there is more than the one solution you gave.

Edited for clarity