Alright, let's solve this math problem step by step. First, we have the number 855. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 28. So, we're going to take the number 855 and add it to itself 28 times.
Step 1: 0 + 855 = 855
Step 2: 855 + 855 = 1710
Step 3: 1710 + 855 = 2565
Step 4: 2565 + 855 = 3420
Step 5: 3420 + 855 = 4275
Step 6: 4275 + 855 = 5130
Step 7: 5130 + 855 = 5985
Step 8: 5985 + 855 = 6840
Step 9: 6840 + 855 = 7695
Step 10: 7695 + 855 = 8550
Step 11: 8550 + 855 = 9405
Step 12: 9405 + 855 = 10260
Step 13: 10260 + 855 = 11115
Step 14: 11115 + 855 = 11970
Step 15: 11970 + 855 = 12825
Step 16: 12825 + 855 = 13680
Step 17: 13680 + 855 = 14535
Step 18: 14535 + 855 = 15390
Step 19: 15390 + 855 = 16245
Step 20: 16245 + 855 = 17100
Step 21: 17100 + 855 = 17955
Step 22: 17955 + 855 = 18810
Step 23: 18810 + 855 = 19665
Step 24: 19665 + 855 = 20520
Step 25: 20520 + 855 = 21375
Step 26: 21375 + 855 = 22230
Step 27: 22230 + 855 = 23085
Step 28: 23085 + 855 = 23940

So, 855*28 = 23940