Let's roll up our sleeves and solve this. We have 267 and we're going to multiply it by 21, essentially adding 267 to itself 21 times.
Step 1: 0 + 267 = 267
Step 2: 267 + 267 = 534
Step 3: 534 + 267 = 801
Step 4: 801 + 267 = 1068
Step 5: 1068 + 267 = 1335
Step 6: 1335 + 267 = 1602
Step 7: 1602 + 267 = 1869
Step 8: 1869 + 267 = 2136
Step 9: 2136 + 267 = 2403
Step 10: 2403 + 267 = 2670
Step 11: 2670 + 267 = 2937
Step 12: 2937 + 267 = 3204
Step 13: 3204 + 267 = 3471
Step 14: 3471 + 267 = 3738
Step 15: 3738 + 267 = 4005
Step 16: 4005 + 267 = 4272
Step 17: 4272 + 267 = 4539
Step 18: 4539 + 267 = 4806
Step 19: 4806 + 267 = 5073
Step 20: 5073 + 267 = 5340
Step 21: 5340 + 267 = 5607

So, 267*21 = 5607