DIVISIBILITY

One whole number is divisible by another if, after dividing, the remainder is zero.

     18 is divisible by 9 since 18 ÷ 9 = 2 with a remainder of 0.

If one whole number is divisible by another number, then the second number is a factor of the first number.

     Since 18 is divisible by 9, 9 is a factor of 18.

A divisibility test is a rule for determining whether one whole number is divisible by another. It is a quick way to find factors of large numbers.
Divisibility Test for 3: if the sum of the digits of a number is divisible by 3, then the number is divisible by 3.

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