OK, let's work through this together. We're starting with 858 and we're going to multiply it by 8, which means we add 858 to itself 8 times.
Step 1: 0 + 858 = 858
Step 2: 858 + 858 = 1716
Step 3: 1716 + 858 = 2574
Step 4: 2574 + 858 = 3432
Step 5: 3432 + 858 = 4290
Step 6: 4290 + 858 = 5148
Step 7: 5148 + 858 = 6006
Step 8: 6006 + 858 = 6864

So, 858*8 = 6864