What does mm mean behind a number?

How many syllables in pounding? Is Axis a math term? How many times does twenty one go into 270? How much time to answer a Jeopardy question? Where are negative numbers used? What is the surface area of a cube with a volume of 250 cubic meters? What percentage of the southern colonies grew wheat? Is there pair lines that intersect but are not perpendicular? How many pairs of perpindicular sides are there in a square? How are tall building cranes erected? What is 21 in Roman numerals? Point at the end of a line segment or ray? How much do 1 dozen oranges cost? What is one times 10 to the 67th power? How many inches is in 4 feet and 5 inches? What year did britain go decimal? What is 2 times 2? How much wpm required for 8000 key depression per hour? What are prime numbers listed from 1 to 52? How long will it take to drive 63 miles driving 65 miles an hour?