OK, let's crack this. We're given 880 and our task is to multiply it by 24. Essentially, we'll be adding 880 to itself 24 times.
Step 1: 0 + 880 = 880
Step 2: 880 + 880 = 1760
Step 3: 1760 + 880 = 2640
Step 4: 2640 + 880 = 3520
Step 5: 3520 + 880 = 4400
Step 6: 4400 + 880 = 5280
Step 7: 5280 + 880 = 6160
Step 8: 6160 + 880 = 7040
Step 9: 7040 + 880 = 7920
Step 10: 7920 + 880 = 8800
Step 11: 8800 + 880 = 9680
Step 12: 9680 + 880 = 10560
Step 13: 10560 + 880 = 11440
Step 14: 11440 + 880 = 12320
Step 15: 12320 + 880 = 13200
Step 16: 13200 + 880 = 14080
Step 17: 14080 + 880 = 14960
Step 18: 14960 + 880 = 15840
Step 19: 15840 + 880 = 16720
Step 20: 16720 + 880 = 17600
Step 21: 17600 + 880 = 18480
Step 22: 18480 + 880 = 19360
Step 23: 19360 + 880 = 20240
Step 24: 20240 + 880 = 21120

So, 880*24 = 21120