OK, let's work through this together. We're starting with 622 and we're going to multiply it by 25, which means we add 622 to itself 25 times.
Step 1: 0 + 622 = 622
Step 2: 622 + 622 = 1244
Step 3: 1244 + 622 = 1866
Step 4: 1866 + 622 = 2488
Step 5: 2488 + 622 = 3110
Step 6: 3110 + 622 = 3732
Step 7: 3732 + 622 = 4354
Step 8: 4354 + 622 = 4976
Step 9: 4976 + 622 = 5598
Step 10: 5598 + 622 = 6220
Step 11: 6220 + 622 = 6842
Step 12: 6842 + 622 = 7464
Step 13: 7464 + 622 = 8086
Step 14: 8086 + 622 = 8708
Step 15: 8708 + 622 = 9330
Step 16: 9330 + 622 = 9952
Step 17: 9952 + 622 = 10574
Step 18: 10574 + 622 = 11196
Step 19: 11196 + 622 = 11818
Step 20: 11818 + 622 = 12440
Step 21: 12440 + 622 = 13062
Step 22: 13062 + 622 = 13684
Step 23: 13684 + 622 = 14306
Step 24: 14306 + 622 = 14928
Step 25: 14928 + 622 = 15550

So, 622*25 = 15550