OK, let's work through this together. We're starting with 80 and we're going to multiply it by 13, which means we add 80 to itself 13 times.
Step 1: 0 + 80 = 80
Step 2: 80 + 80 = 160
Step 3: 160 + 80 = 240
Step 4: 240 + 80 = 320
Step 5: 320 + 80 = 400
Step 6: 400 + 80 = 480
Step 7: 480 + 80 = 560
Step 8: 560 + 80 = 640
Step 9: 640 + 80 = 720
Step 10: 720 + 80 = 800
Step 11: 800 + 80 = 880
Step 12: 880 + 80 = 960
Step 13: 960 + 80 = 1040

So, 80*13 = 1040