How many positive integers are factors of 28. How to find the factors of number 28? Is 28 a prime or a composit number?
asked in Basic Math by questiun

1 Answer

The factors of the number 28 are: 28, 14, 7, 4, 2, 1

The square root of 28 rounded up to the nearest integer is 6. This is the limit to test our divisions because any number greater than 6 times 6 is greater than 28. So, we stop at 6.

Let's test the values 1 through 6 for division into 28.

  • 28÷1 = 28. Remainder = 0. So, 28 and 1 are factors.
  • 28÷2 = 14. Remainder = 0. So, 14 and 2 are factors.
  • 28÷3 = 9. Remainder = 1. So, 9 isn't a factor.
  • 28÷4 = 7. Remainder = 0. So, 7 and 4 are factors.
  • 28÷5 = 5. Remainder = 3. So, 5 isn't a factor.
  • 28÷6 = 4. Remainder = 4. So, 4 isn't a factor.

Factors of a number n are numbers that can divide n without remainder, ie, remainder = 0. So, choosing only the numbers that meet this criteria from the list above, we find that the numbers which divide 28 (including 28) with no remainder are: 28, 14, 7, 4, 2, 1.

So, the factors of the number 28 are: 28, 14, 7, 4, 2, 1.

A composite number has more than two factors. A prime number has only two factors: 1 and itself. The number 1 is neither prime nor composite.

Because the number 28 has 6 factors, it is termed a composite number in mathematics.

As 28 is a composite number, we can factorize it, ie, express it in prime Factors as follows.

By factorizing 28 we get: 28 = 2 × 2 × 7.

Ie, 28 can be expressed as a product (factor string) of prime numbers (2 × 2 × 7).

answered by questiun