OST Grade 3 Math key terms

The result you get when you multiply two or more numbers together. For example, multiplying 4 and 6 gives a product of 24, which can be shown as 4 rows of 6 objects.

A number that is multiplied by another number to make a product. In 3 × 7 = 21, both 3 and 7 are factors, and each divides 21 evenly.

An operation that combines equal groups to find a total. It can be read as repeated addition, so 5 × 3 means three groups of 5 added together.

An operation that splits a total into equal shares or tells how many equal groups fit inside a total. It undoes multiplication, since 20 ÷ 5 = 4 relates to 5 × 4 = 20.

The answer to a division problem. If 36 counters are shared equally among 6 children, each child gets 6, and 6 is the quotient.

The missing number in a number sentence or word problem, often shown with a blank or a letter. Finding it means choosing the operation and value that make the sentence true.

A number sentence stating that two expressions have the same value, joined by an equals sign. For example, 8 × 4 = 32 is an equation that is true.

A combination of numbers and operation signs with no equals sign, such as 6 + 9 or 4 × 5. It can be evaluated to produce a single value.

An arrangement of objects in equal rows and columns that models multiplication. A 3-by-4 array has 3 rows of 4, showing that 3 × 4 = 12.

The rule that changing the order of numbers in addition or multiplication does not change the result. So 6 × 7 equals 7 × 6, and 12 + 9 equals 9 + 12.

The rule that grouping numbers differently in addition or multiplication does not change the result. For example, (2 × 3) × 4 equals 2 × (3 × 4), both giving 24.

The rule that multiplying a number by a sum gives the same result as multiplying by each part and adding. So 6 × 14 equals 6 × 10 plus 6 × 4.

Curved symbols used to group part of an expression so it is calculated first. In 3 × (4 + 2), the sum inside the parentheses is done before multiplying.

The agreed order for calculating in an expression: do work inside parentheses first, then multiplication and division, then addition and subtraction, moving left to right within a step.

A group of related number sentences using the same three numbers. For 3, 5, and 15 the family includes 3 × 5 = 15, 5 × 3 = 15, 15 ÷ 3 = 5, and 15 ÷ 5 = 3.

The value a digit has because of its position in a number. In 4,582 the 5 stands for 500 because it sits in the hundreds place.

A number written with digits in the usual way, such as 3,406. It differs from expanded form, which shows the value of each digit separately.

A way of writing a number as the sum of the values of its digits. For example, 3,406 is written as 3,000 + 400 + 6.

Replacing a number with a nearby number of a chosen place value. To round to the nearest ten, look at the ones digit: 4 or less rounds down, 5 or more rounds up.

A close answer found by rounding or using friendly numbers instead of exact calculation. It helps check whether an exact answer is reasonable.

The result of adding two or more numbers. In 245 + 138 = 383, the number 383 is the sum.

The result of subtracting one number from another. In 500 − 275 = 225, the number 225 is the difference.

Trading ten ones for one ten, or one ten for ten ones, when adding or subtracting. It is often called carrying or borrowing and keeps place values correct.

One of the separate products found when multiplying by each place value of a multi-digit number. In 3 × 24, the partial products are 3 × 20 = 60 and 3 × 4 = 12.

A number that names part of a whole, written as a top number over a bottom number. The bottom tells how many equal parts the whole is cut into.

The top number in a fraction. It counts how many equal parts are being described, as in 3/4, where 3 parts are taken.

The bottom number in a fraction. It names the size of the parts by telling how many equal parts make one whole, as in 3/4, where the whole is split into 4 parts.

A fraction with a numerator of 1, such as 1/2, 1/5, or 1/8. Every other fraction can be built by combining copies of a unit fraction.

Different fractions that name the same amount, such as 1/2 and 2/4. Multiplying or dividing the numerator and denominator by the same number creates them.

A fraction written with the smallest possible whole numbers, where the numerator and denominator share no common factor except 1. For example, 6/8 becomes 3/4.

A straight line marked with evenly spaced numbers, used to show order and size. Fractions can be placed by splitting the space between whole numbers into equal parts.

Deciding which of two fractions is greater or whether they are equal. When denominators match, compare numerators; when numerators match, the smaller denominator means larger parts.

The amount of flat surface a shape covers, measured in square units. For a rectangle, multiplying length by width gives the area.

The distance all the way around the outside of a shape. For a rectangle it equals twice the length plus twice the width, and it is measured in linear units.

A square with sides one unit long, used to measure area. Counting how many square units cover a shape gives its area.

A graph that uses bars of different lengths to show and compare amounts in categories. The height or length of each bar stands for a number.

A graph that uses small pictures or symbols to stand for amounts, with a key explaining what each symbol is worth. Half symbols may show half the key value.

A number line with marks above it showing how often each value appears in a data set. It quickly shows the most common value and the spread of the data.

A closed flat shape made of straight sides that do not cross. Triangles, squares, pentagons, and hexagons are all polygons, named by their number of sides.

A polygon with exactly four straight sides and four corners. Squares, rectangles, trapezoids, and rhombuses are all examples of quadrilaterals.

A quadrilateral with four right angles, where opposite sides are equal and parallel. Squares are special rectangles because all four sides are also equal.

A feature used to describe and sort shapes, such as the number of sides, number of corners, or whether sides are equal in length. Shared attributes define a shape category.