Divisibility Rules
How do you know if a number is divisible by 2?
All even numbers are divisible by 2.
List 4 numbers between 10 - 30 that are divisible by 4.
12, 16, 20, 24, 28
Find the mean of 2, 3, 4, 7
Mean (average) = 4
2 + 3 + 4 + 7 = 16
There are 4 numbers in the number set, so 16 ÷ 4 = 4
564 ÷ 3 =
188
58 ÷ 11
5 R3
How do you know if a number is divisible by 3?
Find the sum of the digits and if the sum is divisible by 3, so is the number.
List 3 numbers that are divisible by 8.
8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, etc.
What is the mean of this number set?
6, 16, 3, 3
Mean (average) = 7
6 + 16 + 3 + 3 = 28
There are 4 numbers in the number set,
so 28 ÷ 4 = 7
3, 425 ÷ 5
685
621 ÷ 6
103 R3
How do you know whether a number is divisible by 6?
1) It is an even number
2) It is also divisible by 3 (add the digits and if the sum is divisible by 3, then so is the number)
How many of the following numbers are divisible by 4?
34 24 18 26 40
24 and 40
4 x 6 = 24
4 x 10 = 40
Find the mean of 33, 22, 11, 22
The mean (average) is 22.
33 + 22 + 11 + 22 = 88
Since there are 4 numbers, divide 88 by 4.
88 ÷ 4 = 22
635 ÷ 2
317 R1
2,142 ÷ 32
66 R 30
The number 234 is divisible by which numbers?
2, 3, 4, 6, 9
2, 3, 6, 9
What are the compatible numbers for 432 ÷ 63
420 ÷ 60
What is the mean of the following number set?
1.5, 2.5, 5, 1
The mean (average) is 2.5 or 2 1/2
Add 1.5 + 2.5 + 5 + 1 = 10
76,325 ÷ 9 =
8480 R5
62,152 ÷ 5 =
12, 430 R2
Which numbers are divisible by 3?
435, 342, 676, 465, 768, 91, 85, 82
435, 342, 465, 768
What are the compatible numbers for 4,546 ÷ 67
4,200 ÷ 70 (best choice)
or
4,200 ÷ 60 (acceptable, but not the best compatible numbers to use)
What is the mean of 1, 2, 5, 9, 7?
4 4/5
or 4.8
6106 ÷ 7 =
872 R2
348,287 ÷ 8
43,535 R7