# 5.2: Divisibility Rules to Find Factors

Difficulty Level:

**At Grade**Created by: CK-12
Difficulty Level: **At Grade**
Created by: CK-12

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I think this was super helpful

Good resource except for an error on the Divisibility Rules Table for the number 7. Divisibility Rule for 7: "Double the last digit, subtract it from the rest of the number." Example Provided: 574; 4 X 2 = 8, 574 - 8 = 566; 566 ÷ 7 = 80 r. 6, this quotient would lead one to think that 574 is not divisible by 7, even though it actually is. The divisibility rule was used incorrectly which resulted to the wrong answer. 8 should have been subtracted from 57 not 574; "the rest of the number" does not include the last digit. 57 - 8 = 49, 49 ÷ 7 = 7. Another example: 672; 2 X 2 = 4, 67 - 4 = 63; 63 ÷ 7 = 9, therefore 672 is divisible by 7.

it was informative and a good read

I believe there is an error on the divisibility rules table for number "3". For 3, we need to take the sum of ALL digits and divide by 3, not the sum of the last two digits. Even the example provided (112) is not divisible by 3.

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