OK, let's crack this. We're given 303 and our task is to multiply it by 5. Essentially, we'll be adding 303 to itself 5 times.
Step 1: 0 + 303 = 303
Step 2: 303 + 303 = 606
Step 3: 606 + 303 = 909
Step 4: 909 + 303 = 1212
Step 5: 1212 + 303 = 1515

So, 303*5 = 1515