# Divisibility Objective Learn to test for divisibility Divisibility

Divisibility Objective: Learn to test for divisibility.

*Divisibility: *One whole number is divisible by another if, after dividing, the remainder is zero. *For example: 18 is divisible by 9 since 18 ÷ 9 = 2 with no remainder. * If one whole number is divisible by another number, then the second number is a factor of the first number. * For example: Since 18 is divisible by 9, 9 is a factor of 18.

divisibility test is a rule for determining whether one whole number is divisible by another. There is a quick way to find factors of large numbers by following these divisibility rules: *A number is divisible by 2… if the last digit is 0, 2, 4, 6 or 8. *A number is divisible by 3…if the sum of the digits is divisible by 3. * A number is divisible by 4… if the number formed by the last 2 digits is divisible by 4. *A number is divisible by 5… if the ones digit is 0 or 5. *A number is divisible by 6… if the number is divisible by BOTH 2 and 3 *A number is divisible by 8… if the number formed by the last 3 digits is divisible by 8. *A number is divisible by 9…if the sum of the digits is divisible by 9. *A number is divisible by 10… if the ones digit is 0.

Example: Test the number 4, 320 for divisibility by 2, 3, 4, 5, 6, 8, 9, and 10. * Is this number divisible by… * 2? * Yes, because the last digit is 0. * 3? * Yes, because 4+3+ 2+0 = 9 and 9 is divisible by 3. * 4? * Yes, because the number formed by the last 2 digits (20) is divisible by 4. * 5? * Yes, because 4, 320 ends in 0. * 6? * Yes, because 4320, is divisible by BOTH 2 and 3. * 8? * Yes, because the number formed by the last 3 digits (320) is divisible by 8 * 9? * Yes, because 4+3+2+0= 9 , which is divisible by 9. * 10? * Yes, because the ones digit is 0. So, 4, 320 is divisible by 2, 3, 4, 5, 6, 8, 9, and 10.

*Your Example *Test each number for divisibility by 2, 3, 4, 5, 6, 8, 9 and 10. 1. 84 3. 128 2. 162 4. 102

* Homework: Test the following numbers for divisibility by 2, 3, 4, 5, 6, 8, 9, and 10. 1. 582 2. 585 3. 330 4. 45 5. 276

- Slides: 6