Five Conversions on Sight

Memorize a short anchor list for instant fluency: 1/2 = 0.5, 1/4 = 0.25, 1/5 = 0.2, 1/8 = 0.125, 1/10 = 0.1. From these, derive everything nearby. 3/8 is three copies of 1/8, so 0.375. 3/5 is three copies of 1/5, so 0.6. 7/10 is seven copies of 1/10, so 0.7.

Next, spot the repeaters on sight. If the denominator's prime factorization includes a 3, 7, 11, or 13, the decimal repeats. 5/12 repeats (12 = 2² × 3). 7/16 terminates (16 = 2⁴).

A few days of this drill turns fraction-to-decimal work from computation into recognition — the way a musician hears a chord without naming the notes.