Physical Science
posted by Amy on .
Can someone explain this rule in simple english please? "Rule for addition and subtraction: The rightmost significant figure in a sum or difference will be determined by the least accurate measurement."
Example: 18.56 m
 13.2 m
__________
5.36 m = 5.4 m

The least accurate measurement is the 13.2 m in this case. Its accuracy is only +/ 0.05.
Therefore the difference should be quoted with the same number of significant digits. In this case, it is the first number after the decimal point. 
addition&subtraction= round to least number of decimal places
multiplication&division=round to least number of significant figures present. 
Suppose you are playing ice hockey in the middle of a totally frictionless frozen pond. How can you move yourself to the edge of the pond ?