is 8721 divided by 5, equal 1744 remainder of 1?

Question

I need to know if I have the correct answer, for I'm sure I have the right process to do so. If this is incorrect it would probably be a minor mistake. Thanks for your help, much needed.

Answer 1

5*1744=8720, add 1=8821 so you have the correct answer. Because 10/2=5, dividing by 5 is the same as multiplying by 2 and dividing by 10; dividing by 10 just moves the decimal point one place to the left. Also, you can work out the remainder after dividing by 5, because all multiples of 5 end in 5 or 0. So look at the last digit of the number you're dividing: if it's less than 5 the remainder is the last digit; if it's 5 or more just subtract 5 to get the remainder. 8721 ends in 1 so the remainder is 1, because 1 is less than 5. Take off the remainder and we get 8720. When we divide this by 10 we lose the last zero. Now multiply 872 by 2 and we get 1744. So we have found 8721/5 with its remainder without dividing by 5!