Let's roll up our sleeves and solve this. We have 455 and we're going to multiply it by 27, essentially adding 455 to itself 27 times.
Step 1: 0 + 455 = 455
Step 2: 455 + 455 = 910
Step 3: 910 + 455 = 1365
Step 4: 1365 + 455 = 1820
Step 5: 1820 + 455 = 2275
Step 6: 2275 + 455 = 2730
Step 7: 2730 + 455 = 3185
Step 8: 3185 + 455 = 3640
Step 9: 3640 + 455 = 4095
Step 10: 4095 + 455 = 4550
Step 11: 4550 + 455 = 5005
Step 12: 5005 + 455 = 5460
Step 13: 5460 + 455 = 5915
Step 14: 5915 + 455 = 6370
Step 15: 6370 + 455 = 6825
Step 16: 6825 + 455 = 7280
Step 17: 7280 + 455 = 7735
Step 18: 7735 + 455 = 8190
Step 19: 8190 + 455 = 8645
Step 20: 8645 + 455 = 9100
Step 21: 9100 + 455 = 9555
Step 22: 9555 + 455 = 10010
Step 23: 10010 + 455 = 10465
Step 24: 10465 + 455 = 10920
Step 25: 10920 + 455 = 11375
Step 26: 11375 + 455 = 11830
Step 27: 11830 + 455 = 12285

So, 455*27 = 12285