A student claims that to divide a number with the units digit 0 by 10, she just crosses out the 0 to get the answer. She wants to know if this is always true and why and if the 0 has to be the units digit. How do you respond?

Answer 1

dividing by 10 shifts the decimal point to the left. That puts the zero after the decimal point, effectively erasing it.

Or, if the number ends in zero, it has the form N0 = N(10) So, dividing by 10 gives

N(10)/10 and the 10's cancel, leaving just N (the number without the zero.)

If the zero is anywhere else, it can't just be dropped, because the factor of 10 isn't there.