Alright, let's solve this math problem step by step. First, we have the number 158. 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 158 and add it to itself 5 times.
Step 1: 0 + 158 = 158
Step 2: 158 + 158 = 316
Step 3: 316 + 158 = 474
Step 4: 474 + 158 = 632
Step 5: 632 + 158 = 790

So, 158*5 = 790