Alright, let's solve this math problem step by step. First, we have the number 138. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 2. So, we're going to take the number 138 and add it to itself 2 times.
Step 1: 0 + 138 = 138
Step 2: 138 + 138 = 276

So, 138*2 = 276