OK, let's work through this together. We're starting with 590 and we're going to multiply it by 15, which means we add 590 to itself 15 times.
Step 1: 0 + 590 = 590
Step 2: 590 + 590 = 1180
Step 3: 1180 + 590 = 1770
Step 4: 1770 + 590 = 2360
Step 5: 2360 + 590 = 2950
Step 6: 2950 + 590 = 3540
Step 7: 3540 + 590 = 4130
Step 8: 4130 + 590 = 4720
Step 9: 4720 + 590 = 5310
Step 10: 5310 + 590 = 5900
Step 11: 5900 + 590 = 6490
Step 12: 6490 + 590 = 7080
Step 13: 7080 + 590 = 7670
Step 14: 7670 + 590 = 8260
Step 15: 8260 + 590 = 8850

So, 590*15 = 8850