Alright, let's solve this math problem step by step. First, we have the number 684. 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 684 and add it to itself 28 times.
Step 1: 0 + 684 = 684
Step 2: 684 + 684 = 1368
Step 3: 1368 + 684 = 2052
Step 4: 2052 + 684 = 2736
Step 5: 2736 + 684 = 3420
Step 6: 3420 + 684 = 4104
Step 7: 4104 + 684 = 4788
Step 8: 4788 + 684 = 5472
Step 9: 5472 + 684 = 6156
Step 10: 6156 + 684 = 6840
Step 11: 6840 + 684 = 7524
Step 12: 7524 + 684 = 8208
Step 13: 8208 + 684 = 8892
Step 14: 8892 + 684 = 9576
Step 15: 9576 + 684 = 10260
Step 16: 10260 + 684 = 10944
Step 17: 10944 + 684 = 11628
Step 18: 11628 + 684 = 12312
Step 19: 12312 + 684 = 12996
Step 20: 12996 + 684 = 13680
Step 21: 13680 + 684 = 14364
Step 22: 14364 + 684 = 15048
Step 23: 15048 + 684 = 15732
Step 24: 15732 + 684 = 16416
Step 25: 16416 + 684 = 17100
Step 26: 17100 + 684 = 17784
Step 27: 17784 + 684 = 18468
Step 28: 18468 + 684 = 19152

So, 684*28 = 19152