Alright, let's solve this math problem step by step. First, we have the number 646. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 7. So, we're going to take the number 646 and add it to itself 7 times.
Step 1: 0 + 646 = 646
Step 2: 646 + 646 = 1292
Step 3: 1292 + 646 = 1938
Step 4: 1938 + 646 = 2584
Step 5: 2584 + 646 = 3230
Step 6: 3230 + 646 = 3876
Step 7: 3876 + 646 = 4522

So, 646*7 = 4522