Without delay, let's solve this. We've got 120 and we will be multiplying it by 13, that is, adding 120 to itself 13 times.
Step 1: 0 + 120 = 120
Step 2: 120 + 120 = 240
Step 3: 240 + 120 = 360
Step 4: 360 + 120 = 480
Step 5: 480 + 120 = 600
Step 6: 600 + 120 = 720
Step 7: 720 + 120 = 840
Step 8: 840 + 120 = 960
Step 9: 960 + 120 = 1080
Step 10: 1080 + 120 = 1200
Step 11: 1200 + 120 = 1320
Step 12: 1320 + 120 = 1440
Step 13: 1440 + 120 = 1560

So, 120*13 = 1560