Divisibility Rules

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# Divisibility Rules - PowerPoint PPT Presentation

Divisibility Rules. Page 10 in textbook. What does it mean to be divisible?. Divisible  A whole number is divisible by another number if the remainder is 0 when the first number is divided by the second. Rule. A whole number is divisible by 2 : if the ones digit is divisible by 2

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## PowerPoint Slideshow about 'Divisibility Rules' - cira

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### Divisibility Rules

Page 10 in textbook

What does it mean to be divisible?
• Divisible 

A whole number is divisible by another number if the remainder is 0 when the first number is divided by the second.

Rule
• A whole number is divisible by 2:
• if the ones digit is divisible by 2
• A whole number is EVEN if it is divisible by 2 (even #s: 0, 2, 4, 6, 8)
• Examples: 2, 4, 6, 8, 10, 12, …
Rule
• A whole number is divisible by 3:
• if the sum of the digits is divisible by 3
• Example: 3, 6, 9, 12, 15, 18, …
Are these numbers divisible by 3?
• 80

8 + 0 = 8 Not divisible by 3!

• 489
• 14,980
• 18,321
Rule
• A whole number is divisible by 4:
• If the number formed by the last two digits is divisible by 4.
• Example: 4, 8, 12, …, 104, 112, …
Are these numbers divisible by 4?
• 605

look at the last 2 digits: 05  NOT divisible by 4!

• 80
• 9, 948
• 11, 292
Rule
• A whole number is divisible by 5:
• If the ones digit is a 0 or 5.
• Example: 5, 10, 15, 20, 25, …
Are these numbers divisible by 5?
• 45

look at the ones place: 5  YES it is divisible by 5!

• 631
• 385
• 459
Rule
• A whole number is divisible by 6:
• If the number is divisible by BOTH 2 and 3.
• Example: 6, 12, 18, 24, 30, …
Are these numbers divisible by 6?
• 126

Check for 2: ends in 6 which is divisible by 2

Check for 3: 1 + 2 + 6 = 9 which is divisible by 3

So, YES it is divisible by 6 because it is divisible by both 2 AND 3!

• 684
• 2, 835
• 1, 114
Rule
• A whole number is divisible by 9:
• If the sum of the digits is divisible by 9.
• Example: 9, 18, 27, 36, 45, …
Are these numbers divisible by 9?
• 60

6 + 0 = 6, So NO it is not divisible by 9

• 138
• 900
• 8, 505
Rule
• A whole number is divisible by 10:
• If the ones digit is 0.
• Example: 10, 20, 30, 40, 50, …
Are these numbers divisible by 10?
• 56

Look at the ones place  6, so NO!

• 220
• 32,360
• 654