OK, let's crack this. We're given 780 and our task is to multiply it by 16. Essentially, we'll be adding 780 to itself 16 times.
Step 1: 0 + 780 = 780
Step 2: 780 + 780 = 1560
Step 3: 1560 + 780 = 2340
Step 4: 2340 + 780 = 3120
Step 5: 3120 + 780 = 3900
Step 6: 3900 + 780 = 4680
Step 7: 4680 + 780 = 5460
Step 8: 5460 + 780 = 6240
Step 9: 6240 + 780 = 7020
Step 10: 7020 + 780 = 7800
Step 11: 7800 + 780 = 8580
Step 12: 8580 + 780 = 9360
Step 13: 9360 + 780 = 10140
Step 14: 10140 + 780 = 10920
Step 15: 10920 + 780 = 11700
Step 16: 11700 + 780 = 12480

So, 780*16 = 12480