Let's roll up our sleeves and solve this. We have 787 and we're going to multiply it by 25, essentially adding 787 to itself 25 times.
Step 1: 0 + 787 = 787
Step 2: 787 + 787 = 1574
Step 3: 1574 + 787 = 2361
Step 4: 2361 + 787 = 3148
Step 5: 3148 + 787 = 3935
Step 6: 3935 + 787 = 4722
Step 7: 4722 + 787 = 5509
Step 8: 5509 + 787 = 6296
Step 9: 6296 + 787 = 7083
Step 10: 7083 + 787 = 7870
Step 11: 7870 + 787 = 8657
Step 12: 8657 + 787 = 9444
Step 13: 9444 + 787 = 10231
Step 14: 10231 + 787 = 11018
Step 15: 11018 + 787 = 11805
Step 16: 11805 + 787 = 12592
Step 17: 12592 + 787 = 13379
Step 18: 13379 + 787 = 14166
Step 19: 14166 + 787 = 14953
Step 20: 14953 + 787 = 15740
Step 21: 15740 + 787 = 16527
Step 22: 16527 + 787 = 17314
Step 23: 17314 + 787 = 18101
Step 24: 18101 + 787 = 18888
Step 25: 18888 + 787 = 19675

So, 787*25 = 19675