Divisibility RUles

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Divisibility RUles - PowerPoint PPT Presentation

Divisibility RUles. Quick ways to see if a number can be evenly divided by another number. When finding factors of a number and reducing fractions. What are divisibility rules? When could we use divisibility rules?. A number is divisible by 2 if its even, meaning it ends in 0, 2, 4, 6, or 8.

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Divisibility RUles

Quick ways to see if a number can be evenly divided by another number.

• When finding factors of a number and reducing fractions.
• What are divisibility rules?
• When could we use divisibility rules?

A number is divisible by 2 if its even, meaning it ends in 0, 2, 4, 6, or 8.

• Yes (ends in 0, so even)
• No (ends in 7, so odd)
• Yes (ends in 2, so even)
• What is the divisibility rule for 2?
• Are the following divisible by 2:58390?
• 267?
• 92?

A number is divisible by 3 if the sum of its digits is divisible by 3.

• Example: 132 is divisible by 3 because 1+3+2=6 and 6 is divisible by 3.
• 1+3+8=12 and 12 is divisible by 3, so 138 is also divisible by 3.
• What is the divisibility rule for 3?
• Is 138 divisible by 3?
• 4+0+2 = 6 and 6 is divisible by 3, so 402 is also divisible by 3.
• Is 97 divisible by 3?
• Is 402 divisible by 3?

A number is divisible by 5 if it ends in a 0 or 5.

• No, it ends in 8.
• Yes, it ends in 5.
• Yes, it ends in 0.
• What is the divisibility rule for 5?
• Are the following divisible by 5: 108?
• 85?
• 310?

A number is divisible by 10 if it ends in a 0.

• No, it ends in 5.
• Yes, it ends in 0.
• Yes, it ends in 0.
• What is the divisibility rule for 10?
• Are the following divisible by 10: 105?
• 80?
• 230?

2 yes (ends in 0 so even)

• 3 no (2+3+0 = 5, which is not divisible by 3)
• 5: yes (ends in 0)
• 10: yes (ends in 0)
• Of 2, 3, 5, and 10, which are factors of 230?

2 no(ends in 5 so odd)

• 3 yes(1+0+5 = 6, which is divisible by 3)
• 5: yes (ends in 5)
• 10:no (does not end in 0)
• Of 2, 3, 5, and 10, which are factors of 105?
Direct Station
• We will learn a few more divisibility rules: how to quickly tell when a number has a factor of 4, 6, or 9.
• We will write down the work for this station in our notebook instead of on our work paper.
Collaborative Station
• Spin the number spinner 3 times. Use the numbers you land on to create a 3 digit number.
• Example: If you spin a 4, a 0, and a 5, your number is 405. If you spin a 0, 8, and 2 your number is 82.
• You and your partner will determine whether your number is divisible by 2, 3, 5, and 10.
Collaborative Station Example
• Say you and your partner spin the number 135.
• Write:
• 135:not divisible by 2 because it ends in 5, not an evendivisible by 3 because 1+3+5=9, which is divisible by 3.divisible by 5 because it ends in 5.not divisible by 10 because it does not end in 0
Independent Station: ST Math
• If you are still on the diagnostic test, finish that.
• Otherwise, continue the properties of operations unit.
• Write down the order of operations problems on your work paper as you do them on the computer.