The ABCs of Mathematics Concepts

Young girl using abacus

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There’s a lot more to math than just addition and subtraction. And of course, as your child gets older, math gets more complicated. To support your child’s mathematical learning, know these math concepts and terms from addend to zero.

Math Terms From A to Z

  • A is for addend: An addend is one of the numbers that will be added in an addition problem. In the problem 3 + 5 = 8, 3 and 5 are addends.
  • B is for brackets: Brackets are symbols used in algebra that are square [ ], round ( ), curly { }, or angled < >. They are used to offset pieces of complicated equations so your child will go through the correct order of operations to solve the problem.
  • C is for cardinal numbers: Many people get cardinal numbers and ordinal numbers confused. Cardinal numbers are number words or numerals that are used for counting or to determine quantity. For example, "1, 2, 3," or "one, two, three."
  • D is for doubles facts: Doubles facts are an important way for your child to memorize addition facts. A doubles fact is when a number is added to itself, such as 1 + 1 = 2, 2 + 2 = 4, 4 + 4 = 8, and 8 + 8 = 16.
  • E is for equation: An equation is a math sentence that has at least one equal sign it. Equations can be simple addition problems or complex algebraic sentences.
  • F is for fact families: Fact families are a set of numbers that are related to each other through a mathematical operation and the equations they can create together.
  • G is for geometry: Geometry is a branch of math that studies two-dimensional shapes and three-dimensional figures. As your child learns more complex math, geometry will play a bigger role in what they are learning.
  • H is for hypotenuse: The hypotenuse is the longest side of a right triangle, the side that is opposite the 90-degree angle.
  • I is for infinity: Infinity is the “number” that is represented by the sideways eight symbol: ∞ It’s bigger than and has a quantity more than any real number. There’s also negative infinity, which is larger than any real negative number.
  • J is for justifications: Although you may think of justifications as what your child gives you as an excuse when they've done something wrong, in math a justification is a statement that proves that a mathematical conclusion is correct. Justifications are mostly used in proving theorems in geometry.
  • K is for key sequence: A key sequence is the directions of what to put into a calculator and in what order. The numbers and key symbols are usually drawn inside little rectangles so that they look like calculator buttons.
  • L is for least common denominator or least common multiple: The least common denominator (LCD) and least common multiple (LCM) are related. The LCM is the smallest positive whole number into which two numbers can be divided evenly. The LCD is the smallest LCM that the bottom number (denominator) of two given fractions share.
  • M is for mean, mode, and median: These three concepts trip many kids up. The mean is the average of a set of numbers. The mode is the number that shows up the most in a list of numbers. The median is the number in a set of numbers below which are exactly half of the rest of the numbers and above which are exactly half of the rest of the numbers. Basically, it’s the middle of the list.
  • N is for nested parentheses: Nested parentheses are sets of parentheses inside other parentheses, like Russian nesting dolls. It’s a way to let your child know which equation to solve first—the innermost set of parentheses.
  • O is for ordered pair: An ordered pair is a set of graph coordinates expressed like (x,y). is always the first number and y is always the second.
  • P is for parallel: You can have parallel lines and parallel planes, both of which have no points in common, meaning they never, ever meet.
  • Q is for quotient: The quotient is the answer to a division problem.
  • R is for remainder: A remainder is the amount left over in a division problem if the number can’t be divided evenly.
  • S is for solution: The solution to the problem is the answer that fills in the blank. In simple math, it’s the number after the equal sign. In more complicated math, it’s the value of the unknown variable(s). For instance, if your child is solving for x in this equation, 2x + 4 = 14, the solution is 5, or the value of x.
  • T is for terms: Terms are the numbers or parts of an equation that are separated by the addition sign, the subtraction sign, or commas. Terms can be the solution to an equation inside nested parentheses.
  • U is for unknown: When your child is working on a complex math problem, sometimes the values of the variables are unknown.
  • V is for variable: A variable is the letter used to stand in for an unknown value. That’s because the value can vary depending on the solution of the rest of the equation.
  • W is for whole numbers: Whole numbers are the integers (or numerals) that are not negative. For example, 0, 1, 2, 3, etc.
  • X is for x-axis: The x-axis is the horizontal (going across) line of a number graph.
  • Y is for y-axis: The y-axis is the vertical (going up) line of a number graph.
  • Z is for zero: Zero (0) is a number with no value. It doesn't stand for any quantity and it’s neither negative nor positive.