If we divide 123 b 10 we get 12.3
Consider the 1 in 123. It represents 100. After we divide the 1 in 12.3 now represents 10.
The 2 in 123 represents 20 but after the division the 2 in 12.3 now represents 10.
Therefore each digit after the division represents 1/10 of what it did. Put another way each digit in the answer represents 10 times less.
