Find the prime factors of 28.
To find the prime factors of 28, we’re going to form a factor tree. Can we identify any prime factors that 28 is divisible by? For example, is 28 divisible by two? 28 divided by two, 28 divided by two equals 14. In other words, two times 14 equals 28. And we recognize that two is a prime number, so we go ahead and circle it.
But 14 is not a prime number; it’s an even number. So we know that it is also divisible by two. 14 divided by two is seven. Two is a prime number and so is seven. 28 equals two times two times seven.
The prime factors that make up 28 are two and seven.