When a fraction is written in simplest form, it's easier to perform operations on that fraction. For instance, multiplying (1/5) and (2/3) is easier than multiplying (25/125) and (18/27).

3 2/125. 16 divides into 1000 62.5 times, but you must used a whole number, so the next nearest is 125, which is 1000 divided by 8. Divide 16 by 8 to match, which is 2.

The decimal 0.125 means 125 parts out of 1000. 125/1000 This is not simplest form yet, divide top and bottom by 5. 25/200 Still not in simplest form yet, divide top and bottom by 5. 5/40 Still not in simplest form, divide top and bottom by 5. 1/8