I was ordering personal checks on some third-party website today; working my way through the endless prompts, when an odd question was posed to me: "What is your fraction number?"
After researching the issue, I came to learn that a fraction number refers to the series of seemingly nondescript numbers and symbols that typically appear at the top of the check, between the account holder's contact information and the check number. Alternatively, it may appear at the right side of the check, below the check number and above the Date line.
It would seem to be synonymous with Bank ID number and is simply a transfiguration of the bank's routing number. See image below.
To determine your (bank's) fraction number — as evidenced in the example above — you would need to know your (bank's) 9-digit routing number. Here are easy steps for figuring it out (those who would rather do it in their heads may follow along accordingly).
On a sheet of paper, write down your (bank's) 9-digit routing number and underline it.
Below the line, number each of the nine digits according to their place in the series (i.e. 1,2,3,4,5,6,7,8,9). Below all of that, transcribe these placeholders and symbols:
_ _ – _ _ _ / _ _ _
Now, here is the secret code that tells you what to put in each placeholder. Each number is indicative of the position in the series. In other words, match the number below to the number you have written below your underlined routing number, and copy the corresponding digit in your routing number to the appropriate spot in the placeholders & symbols that you've written.
2 3 – 6 7 8 / 2 3 4
This concludes today's tutorial. =P