Maths - Significant Figures

Jack McKinlay
Note by , created over 5 years ago

SQA Maths Note on Maths - Significant Figures, created by Jack McKinlay on 08/23/2013.

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Jack McKinlay
Created by Jack McKinlay over 5 years ago
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Revision of Rounding:Before you begin to revise significant figures, you will need to remind yourself of the rules for rounding.Example 1:Round 3.7454 to 2 decimal places.Look at the number given and find the 2nd decimal place. This is the 2nd number after the decimal point, which shows where your number will stop once you have rounded it.3.7454 Remember if the number to the right of the decimal place desired is: 5 or more → Then the number at the desired decimal place will go up by 1 4 or less → Then the number at the desired decimal place will stay the same. As this number to the right of the 2nd decimal point is a 5, then the 4 will go up by 1, which changes it to a 5.Therefore, 3.7454 rounds up to 3.75 to 2 decimal places.Example 2:Round 7.82635 to 1 decimal place.This time we find the 1st decimal place, which is the 1st number after the decimal point.7.82635The number to the right of this is a 2, which means the 8 will stay the same.Therefore, 7.82635 rounds to 7.8 to 1 decimal place.

Rounding to Significant Figures:Numbers which are significant are by in large any number which is not zero. Zeros are usually said to be not significant, apart from two conditions: If the zero is the last digit after the decimal point. If the zero is between two significant numbers. For example 8300 has 2 significant figures 8030 has 3 significant figures 803 has 3 significant figures 80.3 has 3 significant figures 8.03 has 3 significant figures 0.803 has 3 significant figures 803.0 has 4 significant figures 0.8030 has 4 significant figures Example 1:Round 50 790 to 2 significant figures.Find the 2nd significant figure from the number above:50 790As the number to the right is a 7, then it goes up by one, which changes the 0 to a 1 and the remaining numbers are replaced by 0's.Therefore 50 790 rounds to 51 000 to 2 significant figures.Example 2:Round 0.0300 to 1 significant figure.Find the 1st significant figure from the number above:0.0300As the number to the right is a 0, then the 3 will stay the same.Therefore 0.0300 rounds to 0.03 to 1 significant figure.

Significant Figures