[Physics kinda] When are you supposed to fix your units?

I'm sorry if this seems kinda silly but I've been doing homework for several hours now and I feel like I'm forgetting basic algebra. When are you supposed to change all your units over to SI? I realized that I have a radius given in centimeters and an angular velocity in revolutions per minute. Usually, to avoid running into snags, I go ahead and convert those to meters and revolutions per second. However, in one of my equations, the radius is squared. And there's a heck of a margin between 1.44 meters and .0144 meters.

I did the math for both ways just to see if it fixed itself somehow but converted I have a Kinetic Energy value of like 25 vs a KE value of 8.1*10^7.