Multiply by percentage or value between 0 - 1

I need to get the 90% value of a user input given number. So, when the user submits 100.000, the equation should be number x 0,9= 90.000
I noticed that this doesn’t work. Updating equations goes perfect when multiplying bij e.g. 2 or dividing by 10, but multiplying by a 0.9 doesn’t work.
Anyone recommendations how to set this up?

@slimpens Can you paste your equation here? I think if you do ({Value}-{Value}/100*90) it should work.

@Sam, yes the solution you mention is working! Thanks