Up next in Basic Math Skills (15 videos)
Do you and arithmetic add up to disaster? Sharpen your basic bath skills with the lessons in this Howcast video series.
You Will Need
 Ruler
 Calculator
Steps

Step 1
Pick a side
Pick a side to use for your measurement. One side measures 30 centimeters, and the other side of the ruler measures 12 inches.

Step 2
Multiply by 10
Multiply centimeters by 10 to calculate millimeters. For example, 1.2 centimeters equals 12 millimeters.

Step 3
Recognize the line differences
Recognize the different line lengths on the English side of the ruler. The inch line is the longest line with the number next to it. The shorter lines represent fractions of an inch.

Step 4
Identify the 15 other lines
Identify the other 15 lines. They decrease in size from 1/2 to 1/4 of an inch, all the way down to 1/16 of an inch.

Step 5
Convert to fractions
Convert the fractions into decimals using a calculator. Divide the fraction of the inch and then add the whole number. The English side is more complicated than the metric side, since there are 12 inches in a foot rather than the increments of 10 used on the metric side, but once you have mastered the conversions, you can use your knowledge to measure just about any length.