# DIVISIBILITY RULES LESSON 1 Dividing by 2 All

DIVISIBILITY RULES LESSON 1

Dividing by 2 All even numbers are divisible by 2. Any number that ends in 0, 2, 4, 6, or 8. 32 - ends with a 2 therefore an even number 157 - ends with a 7 therefore not an even number

Add up all the digits in the number. Find out what the sum is. If the sum is divisible by 3, so is the number If the sum of the digits of a number add up to a number that can be divided by 3, then so can that number. 36 : adds up to 9 therefore 36 can be divided by 3. 157 - adds up to 13 therefore 157 can not be divided by 3

Are the last two digits in your number divisible by 4? If so, the number is too! If you can divide the last two digits in a number by 4, then the bigger number can also be divided by 4. 136 : 36 can be divided by 4 therefore 136 can be divided by 4. 157 : 57 can not be divided by 4 therefore 157 can not be divided by 4

Numbers ending in a 5 or a 0 are always divisible by 5 If the last digit of a number is 5 or zero (0) then the number can be divided by 5. 135 : ends in a 5 therefore 135 can be divided by 5. 157 : ends in a 7 therefore 157 can not be divided by 5

If the Number is divisible by 2 and 3 it is divisible by 6 also. If the number is even and adds up to a number that you can divide by 3 then it can be divided by 6. 144 : ends in a 4 and adds up to 9 therefore 144 can be divided by 6. 154 : ends in a 4 but adds up to 10 therefore 154 can not be divided by 6. because you can’t divided it by 3.

This one's not as easy: If the last 3 digits are divisible by 8, so is the entire number. You at the last three numbers of a big number and see if they can be divided by 8. 1568 : Since 568 can be divided by 8, so can 1568. 2564 : Since 564 can not be divided by 8, neither can 2568.

Almost the same rule and dividing by 3. Add up all the digits in the number. Find out what the sum is. If the sum is divisible by 9, so is the number. If the sum of the digits of a number add up to a number that can be divided by 9, then so can that number. 369 : adds up to 18 therefore can be divided by 9 2564 : adds up to 17 therefore can not be divided by 9.

If the number ends in a 0, it is divisible by 10. If the last digit of a number is or zero (0) then the number can be divided by 10. 360 : ends in 0 therefore can be divided by 10 2564 : ends in 4 therefore can not be divided by 10.

TRY THESE Ø LIST WHETHER THE FOLLOWING NUMBERS ARE DIVISIBLE BY: 2, 3, 4, 5, 6, 8, 9, 10 Ø 1) 456 Ø 2) 3298 Ø 3) 56 784 Ø 4) 2960

TRY THESE Ø LIST WHETHER THE FOLLOWING NUMBERS ARE DIVISIBLE BY: 2, 3, 4, 5, 6, 8, 9, 10 Ø 1) 456 = {2, 3, 4, 6, 8} Ø 2) 3298 Ø 3) 56 784 Ø 4) 2960

TRY THESE Ø LIST WHETHER THE FOLLOWING NUMBERS ARE DIVISIBLE BY: 2, 3, 4, 5, 6, 8, 9, 10 Ø 1) 456 = {2, 3, 4, 6, 8} Ø 2) 3298 = {2} Ø 3) 56 784 Ø 4) 2960

TRY THESE Ø LIST WHETHER THE FOLLOWING NUMBERS ARE DIVISIBLE BY: 2, 3, 4, 5, 6, 8, 9, 10 Ø 1) 456 = {2, 3, 4, 6, 8} Ø 2) 3298 = {2} Ø 3) 56 784 = {2, 3, 4, 6, 8} Ø 4) 2960

TRY THESE Ø LIST WHETHER THE FOLLOWING NUMBERS ARE DIVISIBLE BY: 2, 3, 4, 5, 6, 8, 9, 10 Ø 1) 456 = {2, 3, 4, 6, 8} Ø 2) 3298 = {2} Ø 3) 56 784 = {2, 3, 4, 6} Ø 4) 2960 = {2, 4, 5, 8, 10}

HOMEWORK Ø Divisibility Rules Handout

- Slides: 15