To find the first three common multiples of 10, 15, and 20, you can list the multiples of each number and identify the ones they have in common.
**Multiples of 10:**
- 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ...
**Multiples of 15:**
- 15, 30, 45, 60, 75, 90, 105, 120, ...
**Multiples of 20:**
- 20, 40, 60, 80, 100, 120, 140, 160, ...
Now, let's identify the common multiples:
- 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ...
- 15, 30, 45, 60, 75, 90, 105, 120, ...
- 20, 40, 60, 80, 100, 120, 140, 160, ...
The first three common multiples are 30, 60, and 90.