A rule can be used to quickly divide a board into equal parts. Lay the rule on the board with the start of the scale against one edge. Then angle the opposite end to a number that is easily divided by the number of parts you want. (If you want to divide a board into three equal parts you might use 9 and mark the board at 3 and 6.) Likewise, if you need four equal parts, angle the rule to numbers divisible by four, like 8, 12 or 16.