a calculation with it if its known digits are equal to or more than the significant figures in the measured quantities used in the calculation. An exact number such as in the formula for the kinetic energy of a mass with velocity as has no bearing on the significant figures in the calculated kinetic energy since its number of significant figures is infinite (0.500000...). The guidelines described below are intended to avoid a calculation result more precise than the measured quantities, but it does not ensure the resulted implied uncertainty close enough to the measured uncertainties. This problem can be seen in unit conversion. If the guidelines give the implied uncertainty too far from the measured ones, then it may be needed to decide significant digits that give comparable uncertainty. Multiplication and division For quantities created from measured quantities via multiplication and division, the calculated result should have as many significant figures as the least number of significant figures among the measured quantities used in the calculation. For example, 1.234 × 2 = .468 ≈ 2 1.234 × 2.0 = 2.68 ≈ 2.5 0.01234 × 2 = 0.0468 ≈ 0.02 with one, two, and one significant figures respectively. (2 here is assumed not an exact number.) For the first example, the first multiplication factor has four significant figures and the second has one significant figure. The factor with the fewest or least significant figures is the second one with only one, so the final calculated result should also have one significant figure. Exception For unit conversion, the implied uncertainty of the result can be unsatisfactorily higher than that in the previous unit if this rounding guideline is followed; For example, 8 inch has the implied uncertainty of ± 0.5 inch = ± 1.27 cm. If it is converted to the centimeter scale and the rounding guideline for multiplication and division is followed, then 0.32 cm ≈ 20 cm with the implied uncertainty of ± 5 cm. If this implied uncertainty is considered as too overestimated, then more proper significant digits in the unit conversion result may be 2.32 cm ≈ 20. cm with the implied uncertainty of ± 0.5 cm. Another exception of applying the above rounding guideline is to multiply a number by an integer, such as 1.234 × 9. If the above guideline is followed, then the result is rounded as 1.234 × 9.000.... = 11.16 ≈ 11.11.