divisibility_rules

# divisibility_rules - Divisibility Rules Simplify your math...

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When to Use These Rules Divisibility rules are only useful if they make things easier. So if anything in this tutorial is too complicated to remember or not useful enough to remember, then FORGET IT! Memorize only what is helpful (or interesting). The general purpose is to find factors without doing any long division.
Rules for 2, 4, and 8 A number is divisible by 2 if it is even. A number is divisible by 4 if its last two digits form a number divisible by 4. (because 4 = 2 2 .) A number is divisible by 8 if its last three digits form a number divisible by 8. (because 8 = 2 3 .) Can you guess at the rule for 16? (16 = 2 4 )

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Shortcut for 8 Dividing three digits by 8 is still too much work! We’re trying to avoid doing any long division at all. Here’s a shortcut: A number is divisible by 8 if the hundred’s place digit is even and the last two digits form a number divisible by 8. (e.g. 216, 688) OR if the hundred’s place digit is odd and the last two digits form a number divisible by 4 but not 8. (examples: 104, 336)
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divisibility_rules - Divisibility Rules Simplify your math...

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