Answer: 2 × 3 × 7
Step-by-step explanation: For the first step of our factoring, we can see that 42 is an even number which means that we can divide it by 2 to get our first two factors.
42 divided by 2 equals 21 so we can factor 42 into 2 × 21.
Since 2 is prime, we can't factor it anymore but we can factor 21 into 3 × 7. Since 3 and 7 are both prime numbers, we are done with factoring.
Finally, we bring down the 2 from the first step and we can see that the prime factorization of 42 is 2 × 3 × 7.