4. If there’s a decimal point, all zeros to the left of the decimal point are significant.
Ex: 100 = 1
100. = 3
5. For numbers with a decimal any zeros to the right are significant
Ex: 5.260 => 4 significant digits
6. For numbers in scientific notation, all numbers are significant
Ex: 0.00000136 => 1.36x10^6
Addition/Subtraction (Match the fewest # of decim