Alright, let's solve this math problem step by step. First, we have the number 864. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 8. So, we're going to take the number 864 and add it to itself 8 times.
Step 1: 0 + 864 = 864
Step 2: 864 + 864 = 1728
Step 3: 1728 + 864 = 2592
Step 4: 2592 + 864 = 3456
Step 5: 3456 + 864 = 4320
Step 6: 4320 + 864 = 5184
Step 7: 5184 + 864 = 6048
Step 8: 6048 + 864 = 6912

So, 864*8 = 6912