Avoiding the term “significant digits” completely: Distinguishing 91 vs 90 is a difference of 1 on a 0-100 scale. 100x10=1000. If you wanted to distinguish 91.0

Avoiding the term “significant digits” completely: Distinguishing 91 vs 90 is a difference of 1 on a 0-100 scale. 100x10=1000. If you wanted to distinguish 91.0 vs 90.9, that’s 1 on a 0-1000 scale, so you’d want 10,000 points.