Alright, let's solve this math problem step by step. First, we have the number 638. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 4. So, we're going to take the number 638 and add it to itself 4 times.
Step 1: 0 + 638 = 638
Step 2: 638 + 638 = 1276
Step 3: 1276 + 638 = 1914
Step 4: 1914 + 638 = 2552

So, 638*4 = 2552