Significant Figures
Key point
- Significant Figures are used to indicate the quantity of something to a reliable and necessary amount of digits (A more precise way of rounding).
- If not specified, always give your answer on IB exams to 3 significant figures.
The number of digits used to express a number carries information about how precisely the number is known
- For example, a stopwatch reading of 3.2s is less precise than a reading of 3.22 seconds
For some values, a number should be more precise (more significant figures), and for others, a number should be less precise (less significant figures)
How many significant figures are used in IB Physics? If not specified, always give your answer on IB exams to 3 significant figures.
There are certain rules which need to be followed to measure the significant figures of a number
- All non-zero (1-9) digits are significant.
- Zeroes between non-zero digits are significant.
- A trailing zero or final zero in the decimal portion only are significant.
A nice trick to help is the Pacific-Atlantic Rule:
- The rule states that if a decimal point is Absent, then the zeroes on the Atlantic/right side are insignificant. If a decimal point is present, then the zeroes on the Pacific/left side are insignificant.
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