NUMBERS AND MEASUREMENT
Significant Digits – Are those digits used to determine the
measure and excludes those zeros that are used as place
holders at the beginning of a decimal and at the end of
integers.
Rules to determine significant digits:
 Rule 1 ALL non zero digits are significant
25.3 has three significant digits.
 Rule 2 ALL zeros between significant digits are
significant. 27.03 has four significant digits.
 Rule 3 ALL zeros at the end of a decimal are significant.
135.000 has six significant digits.
 Rule 4 Zeros that precede the first nonzero digit in a
decimal are not significant. 0.00369 has three significant
digits.
Precision – The precision of a measurement is the place value of
the last significant digit.
Accuracy – The accuracy of a measure is the number of
significant digits in the measure.
Greatest Possible Error (GPE) – Half the place value of the last
digit.
NOTE – When doing multi step calculations, make sure to keep
at least one more significant digit in the intermediate results than
is needed in the answer.