divisibility rules making friends with fractions
TRANSCRIPT
Divisibility Rules
Making friends with fractions
The rule for “2”
2 goes into every even number…..
Even numbers are numbers that end in 0, 2, 4, 6, or 8
The rule for “3”
3 will go into a number if 3 goes into the sum of the digits
Example: 1,266
The sum of the digits is 1 + 2 + 6 + 6 = 15
3 goes into 15….so 3 goes into 1,266
The rule for “4”
If 4 goes into the last two digits it goes into the number
Example: 240…..4 goes into 40 so 4 goes into 240
The rule for “5”
5 goes into any number that ends in “0” or “5”
The rule for “6”
If 2 and 3 go into a number, so does 6
Example: 132….2 goes into it because it is even….3 goes into it because the sum of the digits is 6….6 goes into it because 2 and 3 do
The rule for “7”
Take the last digit and double it….subtract that from the remaining digits…continue until you get a number that is divisible by 7
Example: 133…take the last digit and double it…..3 x 2 = 6
13 – 6 = 7….7 goes into 7 so 7 goes into 133.
The rule for “8”
Not on our list, because it’s a rotten rule!
If 8 goes into the last 3 digits, it goes into the number.
The rule for “9”
Same as the rule for 3…..if 9 goes into the sum of the digits it goes into the number.
Example: 1,233….the sum of the digits is 9…9 goes into 9 so 9 goes into 1,233
The rule for “10”
10 goes into any number that ends in 0
What will divide evenly into:
• 222
• 224
• 1,200
• 7,011
• 156
• 440
• 812