Grade 5, Ch. 1 Math Vocabulary

Transcription

1 Grade 5, Ch. 1 Math Vocabulary rectangular array number model fact family factors product factor pair divisible by divisibility rules prime number composite number square array square number exponent exponential notation unsquaring a number square root factor rainbow factor string length of factor string prime factorization factor tree

2 rectangular array An arrangement of objects into rows and columns. Each row has the same number of objects, and each column has the same number of objects. This is an array of 8 dots. 4 x 2 = 8

3 number model A number sentence that can be used to describe a rectangular array. The first factor is the number of rows in the array and the second factor is the number of columns. This is the number model for this array. 3 x 2 = 6

4 fact family There are four related facts in every fact family, each using the same three numbers. In a multiplication and division fact family there are two multiplication facts and two division facts. This is the fact family for the numbers: 3, 9, and x 9 = 27 9 x 3 = / 3 = 9 27 / 9 = 3

5 factors The numbers being multiplied together in any multiplication problem. The factors for the number model 5 x 2 = 10 are the numbers 5 and 2. product The answer in any multiplication problem. The product for the number model 5 x 2 = 10 is the number 10.

6 factor pair The two numbers being multiplied together in a multiplication problem that will always create the same product. There can be more than one factor pair for a number. There are 3 factor pairs for the number 12. They are: 1 and 12 2 and 6 3 and 4

7 divisible by When a whole number is divided by second whole number and the answer is a whole number, then the first number is divisible by the second number. Examples: The number 135 is divisible by 5 because the answer is 27. The number 122 is not divisible by 5 because the answer is 24.4, which is not a whole number.

8 divisibility rules All numbers are divisible by 1. All even numbers (ending in 0, 2, 4, 6, or 8) are divisible by 2. A number is divisible by 3 if the sum of its digits is divisible by 3. A number is divisible by 5 if it ends in 5 or 0. A number is divisible by 6 if it is divisible by 2 and 3. A number is divisible by 9 if the sum of its digits is divisible by 9. A number is divisible by 10 if it ends in 0.

9 prime number Any number that has exactly two factors, the number itself and one. The numbers 2, 3, 5, 7, and 11 are prime numbers since they have only 2 factors. composite number Any number with more than two factors. The numbers 4, 6, 8, 9, and 10 are composite numbers since they have more than two factors.

10 square array A special rectangular array that always has the same number of rows as columns. 3 x 3 = 9 square number Any number product that is a result of any number times itself. The numbers 4, 9, and 25 are square numbers since 2 x 2 = 4, 3 x 3 = 9, and 5 x 5 = 25.

11 exponent It indicates the number of times you multiply a number by itself. The number 3² can also be written as: 3 times 3, 3 squared, or 3 to the second power. exponential notation Any number written with an exponent. The number 3² is written in exponential notation, but the number 6 is in standard notation.

12 unsquaring a number When you find the number that is multiplied by itself to make the square number. If you unsquare the number 25, the result is the number 5. square root The name for the number that results from unsquaring a number. The number 5 is the square root of the number 25.

13 factor rainbow In a factor rainbow, the product of each connected factor pair should be equal to the number itself. Factor Rainbow for the number 18 is: The lines connect each factor pair for the number 18.

14 factor string A name for a number written as a product of two or more factors. In a factor string, the number 1 may not be used as a factor. Factor Strings for the number 20 are: 2 x 10 4 x 5 2 x 2 x 5 All of these strings are equal to 2o.

15 length of factor string The length is equal to the number of factors in each string. The longest factor string for any number is made up of all prime numbers. Factor String Lengths for the number 20 are: 2 x 10 Length = 2 4 x 5 Length = 2 2 x 2 x 5 Length = 3 All of these strings are equal to 2o.

16 prime factorization The name for the longest factor string of any number. Prime factorizations for: 12: 2 x 2 x 3 18: 2 x 3 x 3 100: 2 x 2 x 5 x 5

17 factor tree This is an easy way to find all of the prime factors of a number. First write the number. Then, underneath write any factor pair of the number. Then, write the factor pairs for each of these numbers. Continue until all of the numbers left are prime numbers. Factor Tree for the number 36: 36 9 x 4 3 x 3 2 x 2