m (meter)
The abbreviation for meter.
m²
Square meter: the area of a square 1 meter on each side.
m³
Cubic meter: the volume of a cube 1 meter on each side, equal to 1000 liters.
Magic square
A square grid of numbers in which every row, column and diagonal adds up to the same total.
Major arc
An arc of a circle that is larger than a semicircle, measuring more than 180°.
Map distance
The distance between two places as measured on a map. The map scale converts it to actual distance.
Mapping diagram
A drawing that shows how each input of a relation is paired with an output, using arrows between two lists.
Margin of error
The amount by which a survey result could differ from the true value, such as ±3%.
Markup
The amount added to the cost of an item to set its selling price, often given as a percent of the cost.
Mass
The amount of matter in an object, measured in grams and kilograms. Unlike weight, it does not change with gravity.
Matrix
A rectangular arrangement of numbers in rows and columns, described by its dimensions, such as 2 × 3.
Maximum
The greatest value in a set of data or the highest value a function reaches.
Mean
The average of a set of numbers: add all the values and divide by how many there are.
Mean absolute deviation
The average distance of the data values from the mean. It measures how spread out the data are.
Measures of center
Single values that describe the middle of a data set: the mean, median and mode.
Median
The middle value when data are put in order. With an even number of values, it is the mean of the two middle ones.
Meter
The base unit of length in the metric system, equal to 100 centimeters, about the height of a doorknob from the floor.
Metric system
A system of measurement based on powers of 10, using units such as the meter, gram and liter with prefixes like kilo-, centi- and milli-.
mg
The abbreviation for milligram.
Midpoint
The point that divides a line segment into two equal parts.
Midpoint formula
The midpoint of the segment joining (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2).
Mile
A US customary unit of length equal to 5,280 feet, or about 1.609 kilometers.
Milligram
A metric unit of mass equal to 1/1000 of a gram. A grain of rice has a mass of about 20–30 mg.
Milliliter
A metric unit of capacity equal to 1/1000 of a liter, about 20 drops from an eye dropper.
Millimeter
A metric unit of length equal to 1/10 of a centimeter, about the thickness of a credit card.
Million
One thousand thousands: 1,000,000, or 10⁶.
Minimum
The least value in a set of data or the lowest value a function reaches.
Minor arc
An arc of a circle that is smaller than a semicircle, measuring less than 180°.
Minuend
The number you subtract from in a subtraction problem.
Minus
Another word for subtract, shown by the sign −. It also names a negative number, as in "minus 3".
Minute
A unit of time equal to 60 seconds. There are 60 minutes in an hour.
Mixed number
A number made of a whole number and a proper fraction, such as 2¼.
mL
The abbreviation for milliliter.
mm
The abbreviation for millimeter.
mm²
Square millimeter: the area of a square 1 mm on each side. 100 mm² = 1 cm².
mm³
Cubic millimeter: the volume of a cube 1 mm on each side. 1000 mm³ = 1 cm³ = 1 mL.
Mode
The value or values that appear most often in a data set. A set can have one mode, several modes or none.
Monomial
An expression with only one term, such as 7, x or 7x²y.
Multiple
The product of a number and any whole number. The multiples of 3 are 3, 6, 9, 12, …
Multiple bar graph
A bar graph that compares two or more data sets side by side, using grouped bars of different colors; also called a double bar graph.
Multiplicand
In a multiplication, the number being multiplied by the other number (the multiplier). Because order does not change the product, the two names are often used loosely.
Multiplication
Combining equal groups to find a total; a shortcut for repeated addition. 3 × 4 means 3 groups of 4.
Multiplicative identity
The number 1, because multiplying any number by 1 leaves it unchanged.
Multiplicative inverse
The reciprocal of a number: the number you multiply it by to get 1. The multiplicative inverse of 5 is 1/5.
Mutually exclusive events
Events that cannot happen at the same time, such as rolling a 1 and rolling a 6 on one die.