Editing Significant figures (section)

=== 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.<ref>{{cite web|url=http://chemistry.bd.psu.edu/jircitano/sigfigs.html|title=Significant Figure Rules|publisher=Penn State University}}</ref> For example, 
:* 1.234 × 2 = {{overline|2}}.468 ≈ 2
:* 1.234 × 2.0 = 2.{{overline|4}}68 ≈ 2.5
:* 0.01234 × 2 = 0.0{{overline|2}}468 ≈ 0.02
:* 0.012345678 / 0.00234 = 5.2{{overline|7}}59 ≈ 5.28
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&nbsp;inch has the implied uncertainty of ±&nbsp;0.5&nbsp;inch = ±&nbsp;1.27&nbsp;cm. If it is converted to the centimeter scale and the rounding guideline for multiplication and division is followed, then {{overline|2}}0.32&nbsp;cm ≈ 20&nbsp;cm with the implied uncertainty of ±&nbsp;5&nbsp;cm. If this implied uncertainty is considered as too overestimated, then more proper significant digits in the unit conversion result may be 2{{overline|0}}.32&nbsp;cm ≈ 20.&nbsp;cm with the implied uncertainty of ±&nbsp;0.5&nbsp;cm.

Another exception of applying the above rounding guideline is to multiply a number by an integer, such as 1.234 ×&nbsp;9. If the above guideline is followed, then the result is rounded as 1.234 × 9.000.... = 11.1{{overline|0}}6 ≈ 11.11. However, this multiplication is essentially adding 1.234 to itself 9 times such as 1.234 + 1.234 + … + 1.234 so the rounding guideline for addition and subtraction described below is more proper rounding approach.<ref>{{Cite web|date=2017-06-16|title=Uncertainty in Measurement- Significant Figures|url=https://chem.libretexts.org/@go/page/83744|website=Chemistry - LibreTexts}}</ref> As a result, the final answer is 1.234 + 1.234 + … + 1.234 = 11.10{{overline|6}} = 11.106 (one significant digit increase).