How to display a ratio but have it calculate as a decimal?

Hi all, i'm trying to display a ratio in my spreadsheet to show the "odds" but i want it to calculate as its decimal, so if i had 1:20 written in it then i want 0.05 to be the value of the cell when i use it in a formula. Is there any way to do this? So far ive only gotten it to show up as a ratio by typing '1:20 with the apostrophe in front of it.

If you are willing to use the '/' character as your ratio delimiter rather than the ':', you can use a number format code like ##/## to display a decimal as a fraction.