OK, let's work through this together. We're starting with 603 and we're going to multiply it by 3, which means we add 603 to itself 3 times.
Step 1: 0 + 603 = 603
Step 2: 603 + 603 = 1206
Step 3: 1206 + 603 = 1809

So, 603*3 = 1809