Let's roll up our sleeves and solve this. We have 516 and we're going to multiply it by 25, essentially adding 516 to itself 25 times.
Step 1: 0 + 516 = 516
Step 2: 516 + 516 = 1032
Step 3: 1032 + 516 = 1548
Step 4: 1548 + 516 = 2064
Step 5: 2064 + 516 = 2580
Step 6: 2580 + 516 = 3096
Step 7: 3096 + 516 = 3612
Step 8: 3612 + 516 = 4128
Step 9: 4128 + 516 = 4644
Step 10: 4644 + 516 = 5160
Step 11: 5160 + 516 = 5676
Step 12: 5676 + 516 = 6192
Step 13: 6192 + 516 = 6708
Step 14: 6708 + 516 = 7224
Step 15: 7224 + 516 = 7740
Step 16: 7740 + 516 = 8256
Step 17: 8256 + 516 = 8772
Step 18: 8772 + 516 = 9288
Step 19: 9288 + 516 = 9804
Step 20: 9804 + 516 = 10320
Step 21: 10320 + 516 = 10836
Step 22: 10836 + 516 = 11352
Step 23: 11352 + 516 = 11868
Step 24: 11868 + 516 = 12384
Step 25: 12384 + 516 = 12900

So, 516*25 = 12900