Let's roll up our sleeves and solve this. We have 924 and we're going to multiply it by 23, essentially adding 924 to itself 23 times.
Step 1: 0 + 924 = 924
Step 2: 924 + 924 = 1848
Step 3: 1848 + 924 = 2772
Step 4: 2772 + 924 = 3696
Step 5: 3696 + 924 = 4620
Step 6: 4620 + 924 = 5544
Step 7: 5544 + 924 = 6468
Step 8: 6468 + 924 = 7392
Step 9: 7392 + 924 = 8316
Step 10: 8316 + 924 = 9240
Step 11: 9240 + 924 = 10164
Step 12: 10164 + 924 = 11088
Step 13: 11088 + 924 = 12012
Step 14: 12012 + 924 = 12936
Step 15: 12936 + 924 = 13860
Step 16: 13860 + 924 = 14784
Step 17: 14784 + 924 = 15708
Step 18: 15708 + 924 = 16632
Step 19: 16632 + 924 = 17556
Step 20: 17556 + 924 = 18480
Step 21: 18480 + 924 = 19404
Step 22: 19404 + 924 = 20328
Step 23: 20328 + 924 = 21252

So, 924*23 = 21252