Alright, let's solve this math problem step by step. First, we have the number 641. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 5. So, we're going to take the number 641 and add it to itself 5 times.
Step 1: 0 + 641 = 641
Step 2: 641 + 641 = 1282
Step 3: 1282 + 641 = 1923
Step 4: 1923 + 641 = 2564
Step 5: 2564 + 641 = 3205

So, 641*5 = 3205