Brush up your maths: answers to significant figures exercise

Give the following numbers to three significant figures:
      654.389
      65.4389
      654,389
      56.7688
      0.03542210
      0.0041032
      45.989

654.389 becomes 654 because the first non-significant digit is 3.

65.4389 becomes 65.4.

654,389 becomes 654,000 because we need to put the zeros in to hold the place values.

56.7688 becomes 56.8 because the first non-significant digit is 6.

0.03542210 becomes 0.0354. Note that three significant figures is not the same as three decimal places, which would give us 0.035.

0.0041032 becomes 0.00410 because the final zero is a significant figure, being the third in the sequence 4, 1, 0, 3, 2.

45.989 becomes 46.0 because we round the third significant digit up from 9 to 10. This increases the digit, 5, preceeding it to 6 and makes the third digit zero.


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Last updated: 3 October, 2007.

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