Alright, let's solve this math problem step by step. First, we have the number 798. 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 798 and add it to itself 25 times.
Step 1: 0 + 798 = 798
Step 2: 798 + 798 = 1596
Step 3: 1596 + 798 = 2394
Step 4: 2394 + 798 = 3192
Step 5: 3192 + 798 = 3990
Step 6: 3990 + 798 = 4788
Step 7: 4788 + 798 = 5586
Step 8: 5586 + 798 = 6384
Step 9: 6384 + 798 = 7182
Step 10: 7182 + 798 = 7980
Step 11: 7980 + 798 = 8778
Step 12: 8778 + 798 = 9576
Step 13: 9576 + 798 = 10374
Step 14: 10374 + 798 = 11172
Step 15: 11172 + 798 = 11970
Step 16: 11970 + 798 = 12768
Step 17: 12768 + 798 = 13566
Step 18: 13566 + 798 = 14364
Step 19: 14364 + 798 = 15162
Step 20: 15162 + 798 = 15960
Step 21: 15960 + 798 = 16758
Step 22: 16758 + 798 = 17556
Step 23: 17556 + 798 = 18354
Step 24: 18354 + 798 = 19152
Step 25: 19152 + 798 = 19950

So, 798*25 = 19950