Let x be an approximation to a value X and let X = x + e. The relative error is |e/X|. When 1.9 is used as an approximation for 1.875, the relative error equals 0.025/1.875 = 0.013, to 3 decimal places or 1.3%. The relative error may be a more helpful figure than the absolute error. An absolute error of 0.025 in a value of 1.9, as above, may be acceptable. But the same absolute error in a value of 0.2, say, would give a relative error of 0.025/0.2 = 0.125 or 12.5%, which would probably be considered quite serious.