OK, let's work through this together. We're starting with 398 and we're going to multiply it by 25, which means we add 398 to itself 25 times.
Step 1: 0 + 398 = 398
Step 2: 398 + 398 = 796
Step 3: 796 + 398 = 1194
Step 4: 1194 + 398 = 1592
Step 5: 1592 + 398 = 1990
Step 6: 1990 + 398 = 2388
Step 7: 2388 + 398 = 2786
Step 8: 2786 + 398 = 3184
Step 9: 3184 + 398 = 3582
Step 10: 3582 + 398 = 3980
Step 11: 3980 + 398 = 4378
Step 12: 4378 + 398 = 4776
Step 13: 4776 + 398 = 5174
Step 14: 5174 + 398 = 5572
Step 15: 5572 + 398 = 5970
Step 16: 5970 + 398 = 6368
Step 17: 6368 + 398 = 6766
Step 18: 6766 + 398 = 7164
Step 19: 7164 + 398 = 7562
Step 20: 7562 + 398 = 7960
Step 21: 7960 + 398 = 8358
Step 22: 8358 + 398 = 8756
Step 23: 8756 + 398 = 9154
Step 24: 9154 + 398 = 9552
Step 25: 9552 + 398 = 9950

So, 398*25 = 9950