How to Calculate the Check Digit of a Routing Number from an Illegible Check

15 de abril de 2013

How to Calculate the Check Digit of a Routing Number from an Illegible Check

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If you ever happen to have a torn or battered check that you can't make out the check-digit (last number) of the routing number for, there is a way to work it out. This number can be calculated and this article explains just how to do that.

Edit Steps

Grab out some scrap paper and a pen for working out the math.

Write down the first eight digits of therouting number that you know already from reading the check. Save a little bit of space in between each number, since the final product will probably require a two digit number to be written down, for each column.

Write down the number 371371371 directly underneath this other line, keeping one number above each other. There should now be two total rows of numbers.

Multiply the top number by the bottom number, for each column. Do not multiply these two columns like you would any 8 digit number by a nine digit number. These columns are separate entries.

Write the answers to the products underneath on a new line. The last column is not necessary, since there is insufficient data to determine this number. Only write down the ones-digit number only of the product.

Add the products together.

Round up the total of the products to the nearest ten. If the sum is an exact figure that is evenly divisible by 10, omit this step.

Subtract the sum of the next highest multiple from the total to the addition of the products together, if the total is not exact. The result should be your check-digit. If the total is an exact figure that is evenly divisible by ten, since there is no difference in the two, the difference will be 0, and therefore, the check digit would be 0 as well.

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Edit Tips

Before doing any calculations, make sure the check isn't ripped to a place where it could be as easy as a dogear. Unfold the rip and look at the routing number. Sometimes, that may help, before doing any arithmetic.

This type of multiplication, is, by the terminology most colleges use, called MOD-10. Most people don't know it by this name but it's of interest to be able to name what you're using!