Moving the place value changes its value by a factor of 10, depending on which side it's moved into.
If you move it to the immediate right, its value would decrease 10 times. Moving it to the immediate left, on the other hand, would increase its value 10 times.
For example, i have 500.
Moving the hundreds digit to the right would give us 050 = 50.
50 is 10times smaller than 500.
Moving the hundreds digit to the left would give us 5000.
5000 is 10times larger than 500.