basic divisibility test
noun phraseA basic divisibility test is a quick rule that tells you if one number can be divided evenly by another number.
Using a basic divisibility test, we can see that 51 is divisible by 3 because its digits add up to 6.
OTHER MEANINGS
2. A simple classroom method for checking whether a whole number is a multiple of a small number such as 2, 3, 5, or 10.
The teacher taught a basic divisibility test for 5: just look at the last digit.
3. A quick mental shortcut used to decide if a division problem will have no remainder.
Before dividing 128 by 4, she used a basic divisibility test and found the last two digits, 28, are divisible by 4.
4. An introductory rule in number theory for identifying factors without doing long division.
The basic divisibility test for 9 says the sum of the digits must be a multiple of 9.