Alright, let's solve this math problem step by step. First, we have the number 781. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 39. So, we're going to take the number 781 and add it to itself 39 times.
Step 1: 0 + 781 = 781
Step 2: 781 + 781 = 1562
Step 3: 1562 + 781 = 2343
Step 4: 2343 + 781 = 3124
Step 5: 3124 + 781 = 3905
Step 6: 3905 + 781 = 4686
Step 7: 4686 + 781 = 5467
Step 8: 5467 + 781 = 6248
Step 9: 6248 + 781 = 7029
Step 10: 7029 + 781 = 7810
Step 11: 7810 + 781 = 8591
Step 12: 8591 + 781 = 9372
Step 13: 9372 + 781 = 10153
Step 14: 10153 + 781 = 10934
Step 15: 10934 + 781 = 11715
Step 16: 11715 + 781 = 12496
Step 17: 12496 + 781 = 13277
Step 18: 13277 + 781 = 14058
Step 19: 14058 + 781 = 14839
Step 20: 14839 + 781 = 15620
Step 21: 15620 + 781 = 16401
Step 22: 16401 + 781 = 17182
Step 23: 17182 + 781 = 17963
Step 24: 17963 + 781 = 18744
Step 25: 18744 + 781 = 19525
Step 26: 19525 + 781 = 20306
Step 27: 20306 + 781 = 21087
Step 28: 21087 + 781 = 21868
Step 29: 21868 + 781 = 22649
Step 30: 22649 + 781 = 23430
Step 31: 23430 + 781 = 24211
Step 32: 24211 + 781 = 24992
Step 33: 24992 + 781 = 25773
Step 34: 25773 + 781 = 26554
Step 35: 26554 + 781 = 27335
Step 36: 27335 + 781 = 28116
Step 37: 28116 + 781 = 28897
Step 38: 28897 + 781 = 29678
Step 39: 29678 + 781 = 30459

So, 781*39 = 30459