Key Concepts
Divisibility Tests | |
---|---|
A number is divisible by | |
2 | if the last digit is 0,2,4,6, or 8 |
3 | if the sum of the digits is divisible by 3 |
5 | if the last digit is 5 or 0 |
6 | if divisible by both 2 and 3 |
10 | if the last digit is 0 |
- Factors If a⋅b=m , then a and b are factors of m , and m is the product of a and b .
- Find all the factors of a counting number.
- Divide the number by each of the counting numbers, in order, until the quotient is smaller than the divisor.
- If the quotient is a counting number, the divisor and quotient are a pair of factors.
- If the quotient is not a counting number, the divisor is not a factor.
- List all the factor pairs.
- Write all the factors in order from smallest to largest.
- Divide the number by each of the counting numbers, in order, until the quotient is smaller than the divisor.
- Determine if a number is prime.
- Test each of the primes, in order, to see if it is a factor of the number.
- Start with 2 and stop when the quotient is smaller than the divisor or when a prime factor is found.
- If the number has a prime factor, then it is a composite number. If it has no prime factors, then the number is prime.
Candela Citations
CC licensed content, Specific attribution
- Prealgebra. Provided by: OpenStax. License: CC BY: Attribution. License Terms: Download for free at http://cnx.org/contents/caa57dab-41c7-455e-bd6f-f443cda5519c@9.757