Alright, let's solve this math problem step by step. First, we have the number 129. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 19. So, we're going to take the number 129 and add it to itself 19 times.
Step 1: 0 + 129 = 129
Step 2: 129 + 129 = 258
Step 3: 258 + 129 = 387
Step 4: 387 + 129 = 516
Step 5: 516 + 129 = 645
Step 6: 645 + 129 = 774
Step 7: 774 + 129 = 903
Step 8: 903 + 129 = 1032
Step 9: 1032 + 129 = 1161
Step 10: 1161 + 129 = 1290
Step 11: 1290 + 129 = 1419
Step 12: 1419 + 129 = 1548
Step 13: 1548 + 129 = 1677
Step 14: 1677 + 129 = 1806
Step 15: 1806 + 129 = 1935
Step 16: 1935 + 129 = 2064
Step 17: 2064 + 129 = 2193
Step 18: 2193 + 129 = 2322
Step 19: 2322 + 129 = 2451

So, 129*19 = 2451