 # Divisibility Rules Page 10 in textbook.

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Divisibility Rules Page 10 in textbook

What does it mean to be 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, …

Are these numbers divisible by 2?
2,320 3,135 78 11,292

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: = 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