how is this percent return calculated?

i suck at math so bear with me. i'm reading a book and it says something along the lines of:

if i take 1 trade and put 25% of my account size into it and then take a 10% gain and do this exactly 10 times then my account would grow by 40%

what's the formula behind this? i'd like to play around with some numbers (change position size, change average gain per trade, etc)…