Alright, let's solve this math problem step by step. First, we have the number 15. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 10. So, we're going to take the number 15 and add it to itself 10 times.
Step 1: 0 + 15 = 15
Step 2: 15 + 15 = 30
Step 3: 30 + 15 = 45
Step 4: 45 + 15 = 60
Step 5: 60 + 15 = 75
Step 6: 75 + 15 = 90
Step 7: 90 + 15 = 105
Step 8: 105 + 15 = 120
Step 9: 120 + 15 = 135
Step 10: 135 + 15 = 150

So, 15*10 = 150