Match the measurements to the correct number of significant figures
a. 408.03 _1
b. 8.0 _2
c. 8.09 _3
d. 0.3 _4
e. 13.60 _5

To calculate the number of sig figs
1.  Count ALL nonzero numbers
2.  If the zero is between 2 numbers, count it
3.  If in a decimal the zero is at the end, count it
4.  In a decimal all the zeros before the first nonzero number are placeholders and don't count them
5.  In a number greater than zero all zeros AFTER the last nonzero number are placeholders and don't count them.

A - 5
B - 2
C - 3
D - 1
E - 4

An em wave does not require a medium, while a mechanical wave does.