OK, let's work through this together. We're starting with 300 and we're going to multiply it by 10, which means we add 300 to itself 10 times.
Step 1: 0 + 300 = 300
Step 2: 300 + 300 = 600
Step 3: 600 + 300 = 900
Step 4: 900 + 300 = 1200
Step 5: 1200 + 300 = 1500
Step 6: 1500 + 300 = 1800
Step 7: 1800 + 300 = 2100
Step 8: 2100 + 300 = 2400
Step 9: 2400 + 300 = 2700
Step 10: 2700 + 300 = 3000

So, 300*10 = 3000