Multiplication of numbers by ten quiz for students. When you multiply by ten, it is the same like multiplying by one and adding a zero behind the outcome. Remember when you multiply by one, the root number is always the same. However the caveat in this case is adding a zero behind the number. No matter how many digits are in a number, the rules are the same. Multiplying by ten is easy once students get the trick. This multiplying by ten exercise is for students in 2nd, 3rd, 4th, 5th and 6th grades to revise.