How do I select a sprite frame based on a range of values?

I have a sprite with 5 animation frames, each a different color;

What i would like to do is select the a frame (from 0 to 4), based on a value from 0 to 100;

so, if the value is 0-20, choose frame 0;

if the value is 21-40, choose frame 1, and so on all the way up to 81-100;

It feels that I should be using a statement with 'clamp' and modulus%20 to select the frame, but i can't figure out how;

BTW, I know I can choose multiple if/else statements, but I think it can be done more efficiently;

thanks;

The range is 0 to 4, so you want: floor(min(x,99)/20)

thanks, i was thinking about this and decided to go for a walk and came up with the following:

frame = ceil(x/20)

but your way works too!