Divisibility Rules and Concepts

Front

An integer is divisible by 9 if...

Back

if the sum of the digits is divisible by 9.

Front

The numbers 0 and 1 are

Back

Neither prime nor composite.

Front

Which of these is divisible by 2? 243, 89, 50808, 5439

Back

50808.

Front

What is the divisibility rule for 5?

Back

The last digit needs to be a 5 or 0.

Front

Is 95 divisible by 5?

Back

Yes.

Front

What is the divisibility rule for 3?

Back

A number is divisible by 3 if the sum of its digits is divisible by 3.

Front

What are prime numbers?

Back

Numbers greater than 1 that have no positive divisors other than 1 and themselves.

Front

What are composite numbers?

Back

Numbers greater than 1 that have more than two positive divisors.

Front

Is 1 a prime number?

Back

No, 1 is neither prime nor composite.

Front

What is the divisibility rule for 4?

Back

A number is divisible by 4 if the last two digits form a number that is divisible by 4.