Page 21 - Science Course 1 (Book 1)

Mo. 1 - L2b What are precision and Accuracy?

Example Significant Applied
Digits Rules
Measurement and Uncertainty 1.234 4 1

No measuring tool provides a perfect measurement. 1.2 2 1
All measurements have some degree of uncertainty. 0.023 2 1, 4
0.200 3 1, 3
1,002 4 1, 2
3.07 3 1, 2
0.001 1 1, 4
0.012 2 1, 4
50,600 3 1, 2, 4
Using significant digits lets others know how certain
your measurements are.
0.3 cm is
estimated digit

0.2 cm is a known
3 4 5 6 digit

5 6 5 cm is a known
digit

Significant digits are the number of digits in a Key Concept
measurement that are known with a certain degree What are precision and Accuracy?
of reliability. Why should you use significant digits?

The significant digits in a measurement include all
digits you know for certain plus one estimated digit.

Significant
all nonzero integers

Not Significant Significant
zeroes for “cosmetic“ all zeroes between
purposes non zero numbers

0 . 0 0 4 0 0 4 5 0 0

Not Significant Significant
zeroes used only to locate zeroes at the end of a
the decimal point number to the right of
decimal point

Significant Digits SUMMARY
Rules What are Precision and Accuracy?
1. All nonzero number are significant . Precision is a description of how similar
2. Zeros between nonzero digits are significant. or close measurements are to each other.
3. Final zeros used after the decimal point are Accuracy is a description of how close a
significant. measurement is to an accepted value.
4. Zeros used after the decimal point are not
significant. The zeros indicate only the position of the
decimal point.

Good Accuracy Poor Accuracy Poor Accuracy
Good Precision Poor Precision Good Precision
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