If you're calculating by hand (ie: figuring out material needed for a winding staircase or something) - working with two integers / a ratio can mean you can eas

If you're calculating by hand (ie: figuring out material needed for a winding staircase or something) - working with two integers / a ratio can mean you can easily simplify the math, and only deal with narly decimal precision after simplifying. Eg area of a half circle is: A = pi * r^2/2 Or, for example, radius 4 units (eg feet): 22 * 4^2 --------- 7 * 2 Simplifies to: 88/7. Easy to approximate, easy to work out to needed precision.