1. **State the problem:** Find the least common multiple (LCM) of 10 and 4. 2. **Formula and rules:** The LCM of two numbers is the smallest positive integer that is divisible by both numbers. 3. **Find prime factorizations:** - 10 = $2 \times 5$ - 4 = $2^2$ 4. **Take the highest powers of all prime factors:** - For 2, the highest power is $2^2$ - For 5, the highest power is $5$ 5. **Calculate the LCM:** $$\text{LCM} = 2^2 \times 5 = 4 \times 5 = 20$$ 6. **Answer:** The LCM of 10 and 4 is 20.