Divisibility rules
What is the divisibility rule for 2?
A number is divisible by 2 if it ends in 0, 2, 4, 6, or 8.
What are the factor pairs of 12?
The factor pairs of 12 are (1, 12), (2, 6), and (3, 4).
What is the first arc you always write?
1 and the number
Define common factors.
Common factors are the numbers that divide two or more numbers without a remainder.
What does the term "greatest common factor" mean?
The greatest common factor (GCF) is the largest number that divides two or more numbers without a remainder.
What is the divisibility rule for 6?
It is divisible by 2 AND 3
List all the factor pairs for 18.
The factor pairs for 18 are (1, 18), (2, 9), and (3, 6).
Draw a factor rainbow for the number 20.
For the number 20, the factor rainbow would include the pairs: (1, 20), (2, 10), and (4, 5).
What are the common factors of 8 and 12?
1 and 4.
What is the greatest common factor (GCF) of 8 and 12?
4
If a number ends in 0 or 5, what does that tell you about its divisibility?
What is one factor pair of 24?
A factor pair of 24 is (1, 24), (2, 12), (3, 8), or (4, 6).
Explain how to create a factor rainbow for the number 28.
To create a factor rainbow for the number 28, list its factors: (1, 28), (2, 14), (4, 7).
Find the common factors of 15 and 25.
1 and 5
30 and 60
30
Explain the rule for determining if a number is divisible by 3.
A number is divisible by 3 if the sum of its digits is divisible by 3.
How many factor pairs does the number 30 have?
The number 30 has 4 factor pairs: (1, 30), (2, 15), (3, 10), and (5, 6).
What is the purpose of a factor rainbow?
The purpose of a factor rainbow is to help visualize the factors of a number and their relationships.
How do you determine the common factors of two numbers?
To determine the common factors of two numbers, list the factors of each number and find the numbers that appear in both lists.
33 and 88
11
What is the rule for checking if a number is divisible by 9?
A number is divisible by 9 if the sum of its digits is divisible by 9.
Identify the factor pairs of 36.
The factor pairs of 36 are (1, 36), (2, 18), (3, 12), (4, 9), and (6, 6).
Describe how to find the factors of a number to create a factor rainbow.
To find the factors of a number, divide it by integers starting from 1 and record the pairs that multiply to the original number.
List the common factors of 30 and 45.
1, 3, 5 and 15
48 and 120
24