Work Step by Step
Apply the rules on page 162 of the book to find the significant digits (the accuracy) of the measurement 20.050 km. We use rule #1: all non-zero digits are significant. Thus "2,5" are significant. We also use rule #2: all zeros between significant digits are significant; thus, we have here 2 zeros which are significant. We also use rule #4: all zeros to the right of a significant digit and decimal point are significant; that is, we have here 1 zero, which is significant. Thus, there are 5 significant digits.