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Description

Narration

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Slides 1 and 2 describe the definition of Significant Figures.

This lesson is about significant figures. Significant figures only deal with measured numbers. Significant figures indicate the precision of a measurement. So when you're recording significant figures, significant figures in a measurement include the known digits plus a final estimated digit.

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Slide 3 is titled: “Counting Significant Figures”, the rules for counting significant figures are shown on the slide.

Counting significant figures-- you're going to count all the numbers as significant except leading zeros and trailing zeros that come without a decimal point.

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Slide 4 shows examples of Significant Figures. The narrator reads the 4 numbers and tells how many Significant Figures each number has.

So let's do some examples. So 23.50 here has four significant figures. 402 has three significant figures. 5,280 has three significant figures. We're not going to count that zero because there is no decimal point. And then we have 0.080 which is two significant figures. We're not going to count the leading zeros.

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Slide 5 is titled “Calculating with Sig Figs”. How to add or subtract significant figures is displayed on the slide and the narrator walks through an example problem.

Significant figures math-- when calculating significant figures, there are some steps that we have to follow. So for addition and subtraction, the final answer should have the same number of significant figures as the measurement with the smallest number of digits to the right of the decimal. So 27.4 plus 18.26 equals 45.66. However, when we apply our rules of significant figures we notice that we have one significant figure to the right and then two here, which means that our final answer should have one digit to the right of the final answer, giving us a 45.7.

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Slide 6 walks through the steps in multiplying and dividing significant figures and the narrator goes through an example problem.

When we do multiplication or division, the number with the fewest significant figures determines the number of significant figures in the answer. So for example, 13.91 times 23.3 equals 324.103. However, we have four significant figures here. We have three significant figures here. Therefore, our final answer will have three significant figures. So we will end our answer with 324 only.

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Slide 7 summarizes exact numbers.

Exact numbers do not limit the number of sig figs in the answer. So when you're counting numbers, 12 students is 12 students. Exact conversions-- 1 meter is equal to 100 centimeters. And then 1 in any type of conversion is equal to-- 1 inch equals 2.54 centimeters.

All numbers in scientific notation are significant. And then you're only going to use sig figs after all calculations are done. In other words, only round to get the appropriate amount of significant figures once all calculations are complete.