OK, let's crack this. We're given 15 and our task is to multiply it by 33. Essentially, we'll be adding 15 to itself 33 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
Step 11: 150 + 15 = 165
Step 12: 165 + 15 = 180
Step 13: 180 + 15 = 195
Step 14: 195 + 15 = 210
Step 15: 210 + 15 = 225
Step 16: 225 + 15 = 240
Step 17: 240 + 15 = 255
Step 18: 255 + 15 = 270
Step 19: 270 + 15 = 285
Step 20: 285 + 15 = 300
Step 21: 300 + 15 = 315
Step 22: 315 + 15 = 330
Step 23: 330 + 15 = 345
Step 24: 345 + 15 = 360
Step 25: 360 + 15 = 375
Step 26: 375 + 15 = 390
Step 27: 390 + 15 = 405
Step 28: 405 + 15 = 420
Step 29: 420 + 15 = 435
Step 30: 435 + 15 = 450
Step 31: 450 + 15 = 465
Step 32: 465 + 15 = 480
Step 33: 480 + 15 = 495

So, 15*33 = 495