We use power-of-two denominators. 1/2, 1/4, 1/8, 1/16, 1/32. We don’t use 1/3, 1/6, 1/9, 1/12, 1/5, 1/7.

We intrinsically know that 1/2 and 16/32 are equivalent; we would have to think about 3/6 or 6/12.