The product of a set of distinct positive integers is $630$.  If one of the numbers is 42, what are the other two numbers?

1 answer

To determine the other two numbers in the set of distinct positive integers that multiply to 630, given that one of the numbers is 42, we start by factoring 630:

1. **Prime Factorization of 630:**
- First, divide by 2: \( 630 \div 2 = 315 \)
- Then, divide by 3: \( 315 \div 3 = 105 \)
- Again, divide by 3: \( 105 \div 3 = 35 \)
- Next, divide by 5: \( 35 \div 5 = 7 \)

Thus, the prime factorization of \( 630 \) is:
\[
630 = 2 \times 3^2 \times 5 \times 7
\]

2. **Evaluate and Confirm 42's Factors:**
- \( 42 = 2 \times 3 \times 7 \)

3. **Determine the Product of Remaining Integers:**
Given one number is 42, calculate the quotient of \( 630 \div 42 \) to find the product of the other two numbers:
\[
\frac{630}{42} = 15
\]

4. **Factorize 15:**
- The factors of \( 15 \) are \( 3 \times 5 \).

Thus, if one of the numbers is 42, the other two numbers must be 3 and 5, since:

- \( 42 \times 3 \times 5 = 630 \)

Therefore, the set of distinct positive integers is \( \{3, 5, 42\} \).

To verify, re-expand the verification steps:
\[
42 \times 3 = 126, \quad 126 \times 5 = 630
\]

Thus, the other two numbers are \( \boxed{3 \text{ and } 5} \).