Replace a number with a nearby simpler approximation.
round(value × 10^p) / 10^p · or nearest k/n
Place rounding scales by 10^p, applies a rounding mode (half-up, half-even, floor, ceiling), then scales back. Fraction rounding snaps to the nearest k/n. Significant figures keep a fixed count of meaningful digits.
Reporting measurements, money, engineering tolerances, and display formatting.
Calculators