The standardized unit of measurement across the world is the metric system. This system utilizes a standard unit of measure for a physical property to eliminate the arbitrary conversions that must be done within the American system. It is often times necessary to convert from meters to inches to help Americans grasp the length of an item by putting it in more familiar terms. This process can be done rather easily once you familiarize yourself with the conversion scale.

Write down "220" on a piece of paper, representing the number of millimeters that you are dealing with in your equation.

Write down the number "4" on the line below the 220. Align this number all the way to the right so that the 4 is below the 0 in 220.

Multiple the 220 times 4, which will result in the number 880.

Move the decimal point two places to the left since you are actually multiplying the 220 times .04, giving you the answer 8.8, which is the number of inches equaling 220 millimeters.
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