OST Grade 5 Math key terms

The value a digit has because of its position in a number. In 4,382 the 3 is worth 300, but in 3,482 the 3 is worth 3,000.

A number written with digits only, using place value, such as 27,406. This is the usual way numbers appear in problems and answers.

A number broken apart to show the value of each digit, written as a sum. For example, 5,308 = 5,000 + 300 + 8.

A number written using words instead of digits, such as twenty-seven thousand four hundred six. Hyphens join the tens and ones parts.

The dot that separates the whole-number part of a decimal from the fractional part. Digits to its right name tenths, hundredths, thousandths, and so on.

A number written with a decimal point that shows a whole part and a part less than one. For example, 3.75 means 3 whole units plus 75 hundredths.

The place one step to the right of the decimal point, showing how many parts out of ten. In 0.6 the digit 6 means six tenths.

The place two steps to the right of the decimal point, showing parts out of one hundred. In 0.47 the 7 means seven hundredths.

The place three steps to the right of the decimal point, showing parts out of one thousand. In 2.135 the 5 means five thousandths.

Replacing a number with a nearby, simpler number of a chosen place value. Look at the digit to the right: 5 or more rounds up, less than 5 stays the same.

Deciding which of two numbers is greater using place value, from left to right. Symbols <, >, and = record the result, as in 0.6 > 0.58.

A straight line marked with evenly spaced points that stand for numbers. It shows order, distance, and where a value falls between two others.

A number made by multiplying tens, such as 10, 100, or 1,000. Multiplying by one shifts every digit one place to the left.

A small raised number that tells how many times the base is used as a factor. In 10³ the exponent 3 means 10 × 10 × 10.

The number that is repeatedly multiplied when a power is written. In 2⁴ the base is 2, and the exponent 4 says to use it four times.

A close answer found by rounding or by using friendly numbers instead of exact values. Estimates help check whether a computed answer is reasonable.

Numbers adjusted to be easy to compute with mentally, often ending in zeros or dividing evenly. For 4,187 ÷ 6, using 4,200 ÷ 6 gives a quick estimate.

The result of a division problem. In 56 ÷ 8 = 7, the quotient is 7, telling how many groups of 8 fit into 56.

The number being divided in a division problem. In 56 ÷ 8, the dividend is 56, the amount being split into equal groups.

The number you divide by, telling the size of each group or how many groups. In 56 ÷ 8, the divisor is 8.

The amount left over when a number does not divide evenly. Dividing 47 by 5 gives a quotient of 9 with a remainder of 2.

The result of multiplying two or more numbers. In 6 × 7 = 42, the product is 42, the total of six groups of seven.

A number multiplied with another to make a product. The factors of 12 are 1, 2, 3, 4, 6, and 12 because each divides 12 evenly.

The result of multiplying a whole number by 1, 2, 3, and so on. Multiples of 4 include 4, 8, 12, 16, and 20.

A whole number greater than 1 with exactly two factors, 1 and itself. Examples include 2, 3, 5, 7, and 11; 1 and 9 are not prime.

A whole number greater than 1 that has more than two factors. For example, 12 is composite because 1, 2, 3, 4, 6, and 12 all divide it.

A number that names part of a whole or part of a group, written as a numerator over a denominator. In 3/4, three of four equal parts are counted.

The top number of a fraction, telling how many equal parts are being counted or described. In 3/5 the numerator is 3.

The bottom number of a fraction, telling how many equal parts make one whole. In 3/5 the denominator is 5.

Different fractions that name the same amount, such as 1/2, 2/4, and 5/10. Multiplying or dividing numerator and denominator by the same number creates them.

A fraction written with the smallest possible whole-number numerator and denominator. For example, 6/8 in simplest form is 3/4.

A shared denominator that two or more fractions are rewritten to have before adding or subtracting. For 1/3 and 1/4, a common denominator is 12.

The smallest number that is a multiple of two or more given numbers. The least common multiple of 4 and 6 is 12, useful as a common denominator.

The largest number that divides two or more given numbers evenly. The greatest common factor of 18 and 24 is 6, used to simplify fractions.

A number made of a whole number and a fraction together, such as 2 1/3. It equals the whole amount plus the fractional part.

A fraction whose numerator is equal to or greater than its denominator, such as 7/4. Its value is 1 or more and can be rewritten as a mixed number.

A fraction with a numerator of 1, such as 1/2, 1/5, or 1/8. Any fraction can be built by adding or multiplying unit fractions.

The amount of space a solid figure takes up, measured in cubic units. For a rectangular prism, multiply length by width by height.

A solid box shape with six rectangular faces, where every corner is a right angle. Its volume equals length × width × height.

A cube measuring one unit on every edge, used to measure volume. A prism holding 24 such cubes has a volume of 24 cubic units.

A flat surface divided by a horizontal axis and a vertical axis, used to locate points with ordered pairs. The axes meet at the origin, (0, 0).

Two numbers in a fixed order that locate a point on a coordinate plane, written as (x, y). The first number gives horizontal position, the second vertical.

The horizontal number line on a coordinate plane. The first number in an ordered pair tells how far to move right or left along it.

The vertical number line on a coordinate plane. The second number in an ordered pair tells how far to move up or down along it.

The point where the x-axis and y-axis cross on a coordinate plane, named by the ordered pair (0, 0). Distances are often counted from here.