OK, let's work through this together. We're starting with 450 and we're going to multiply it by 12, which means we add 450 to itself 12 times.
Step 1: 0 + 450 = 450
Step 2: 450 + 450 = 900
Step 3: 900 + 450 = 1350
Step 4: 1350 + 450 = 1800
Step 5: 1800 + 450 = 2250
Step 6: 2250 + 450 = 2700
Step 7: 2700 + 450 = 3150
Step 8: 3150 + 450 = 3600
Step 9: 3600 + 450 = 4050
Step 10: 4050 + 450 = 4500
Step 11: 4500 + 450 = 4950
Step 12: 4950 + 450 = 5400

So, 450*12 = 5400