Precision Math Example 3

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Example 3

easy
Which measurement is more precise: 77 m, 7.07.0 m, or 7.007.00 m? How many significant figures does each have?

Solution

  1. 1
    77 m: 11 significant figure (precise to the ones place).
  2. 2
    7.07.0 m: 22 significant figures (the trailing zero after the decimal is significant; precise to the tenths).
  3. 3
    7.007.00 m: 33 significant figures (precise to the hundredths place). This is the most precise.

Answer

7.007.00 m is most precise (33 sig figs); 7.07.0 m has 22 sig figs; 77 m has 11 sig fig.
Trailing zeros after a decimal point are always significant — they indicate the precision of the measurement. Writing 7.007.00 m instead of 77 m communicates that the measurement is known to the nearest centimetre, not just the nearest metre.

About Precision

The degree of exactness in a measurement or calculation, reflected in the number of significant digits reported.

Learn more about Precision →

More Precision Examples

Example 1 medium

A student measures a pencil three times and gets [formula] cm, [formula] cm, [formula] cm. Another i

Example 2 hard

Add [formula] cm and [formula] cm, applying the rule for precision in addition.

Example 4 medium

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