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."

Question

Example: 18.56 m
- 13.2 m
__________
5.36 m = 5.4 m

Answer 1

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.

Answer 2

addition&subtraction= round to least number of decimal places

multiplication&division=round to least number of significant figures present.

Answer 3

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 ?