Alright, let's solve this math problem step by step. First, we have the number 378. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 3. So, we're going to take the number 378 and add it to itself 3 times.
Step 1: 0 + 378 = 378
Step 2: 378 + 378 = 756
Step 3: 756 + 378 = 1134

So, 378*3 = 1134