OK, let's work through this together. We're starting with 603 and we're going to multiply it by 9, which means we add 603 to itself 9 times.
Step 1: 0 + 603 = 603
Step 2: 603 + 603 = 1206
Step 3: 1206 + 603 = 1809
Step 4: 1809 + 603 = 2412
Step 5: 2412 + 603 = 3015
Step 6: 3015 + 603 = 3618
Step 7: 3618 + 603 = 4221
Step 8: 4221 + 603 = 4824
Step 9: 4824 + 603 = 5427

So, 603*9 = 5427