Alright, let's solve this math problem step by step. First, we have the number 809. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 25. So, we're going to take the number 809 and add it to itself 25 times.
Step 1: 0 + 809 = 809
Step 2: 809 + 809 = 1618
Step 3: 1618 + 809 = 2427
Step 4: 2427 + 809 = 3236
Step 5: 3236 + 809 = 4045
Step 6: 4045 + 809 = 4854
Step 7: 4854 + 809 = 5663
Step 8: 5663 + 809 = 6472
Step 9: 6472 + 809 = 7281
Step 10: 7281 + 809 = 8090
Step 11: 8090 + 809 = 8899
Step 12: 8899 + 809 = 9708
Step 13: 9708 + 809 = 10517
Step 14: 10517 + 809 = 11326
Step 15: 11326 + 809 = 12135
Step 16: 12135 + 809 = 12944
Step 17: 12944 + 809 = 13753
Step 18: 13753 + 809 = 14562
Step 19: 14562 + 809 = 15371
Step 20: 15371 + 809 = 16180
Step 21: 16180 + 809 = 16989
Step 22: 16989 + 809 = 17798
Step 23: 17798 + 809 = 18607
Step 24: 18607 + 809 = 19416
Step 25: 19416 + 809 = 20225

So, 809*25 = 20225