OK, let's crack this. We're given 263 and our task is to multiply it by 15. Essentially, we'll be adding 263 to itself 15 times.
Step 1: 0 + 263 = 263
Step 2: 263 + 263 = 526
Step 3: 526 + 263 = 789
Step 4: 789 + 263 = 1052
Step 5: 1052 + 263 = 1315
Step 6: 1315 + 263 = 1578
Step 7: 1578 + 263 = 1841
Step 8: 1841 + 263 = 2104
Step 9: 2104 + 263 = 2367
Step 10: 2367 + 263 = 2630
Step 11: 2630 + 263 = 2893
Step 12: 2893 + 263 = 3156
Step 13: 3156 + 263 = 3419
Step 14: 3419 + 263 = 3682
Step 15: 3682 + 263 = 3945

So, 263*15 = 3945