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Check Numbers

Can you explain "Check Numbers" to me? We're getting ready to do lesson 40 something in Level D & I'm wondering what this is.

Thanks,
Carrie

Re: Check Numbers

Dear Carrie,

Check numbers are really quite fun. I think you and your child will enjoy learning about them and using them as an easy way to correct the computation of rows of numbers. It's a fast and efficient way to "check" if the basic math computation is correct. Another name for check numbers is "casting out 9's". Maybe you've heard of this? You add up the digits of a number and cast out the 9's and are left with a check number between 1 and 8. When you computer the check numbers they will figure out to have the correct check number of the final answer assuring you that you either got the correct answer or that you need to go back and check your computation. You will have a greater understanding of check numbers once you go through the three lessons that explain them in Level D.

Feel free to call, email or post any other questions you have re: check numbers or anything else related to RS.

Sincerely,
Rosine

Re: Re: Check Numbers

Check Numbers are great fun, but somewhat confusing at first. Here is my step by step explanation with a problem illustrating it. Remember it is just another way to check to see if the problem is right. It also shows the interconnectedness in math. As your child sees this amazing pattern it will cause him to begin looking for other patterns and thinking more abstractly. It is worth the time and effort to teach. It works because our number system is a base 10 system. We only use ten basic digits and then repeat them to form the other numbers. Here goes with my first attempt at an explanation. Try it and if you are confused, give us a call at our customer service line 888-272-3291.