Memorize
 Times tables up to 12
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 Primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37 …
Divisibility Rules
 2—If the number ends in 0, 2, 4, 6, or 8, then the number is divisible by 2
 3—Add the digits; if the result is divisible by 3, then the whole number is
divisible by 3
 4—If the last two digits would be divisible by 4, then the whole number is
divisible by 4
 5—If the number ends in 0 or 5, then the number is divisible by 5
 6—If the number is divisible by both 2 and 3, then the number is divisible
by 6
 9—Add the digits; if the result is divisible by 9, then the whole number is
divisible by 9
 10—If the number ends in a 0, then the number is divisible by 10