Bank, district 1
- Input
- 011000015
- Expected output
- Prefixo 01: banco padrão, distrito 1 (Boston), checksum 20 válido
The leading zero is part of the number and must be kept.
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what the first digits of a routing number mean
Before any arithmetic, the prefix already answers two questions: which Federal Reserve region the bank sits in and whether the number belongs to an ordinary bank, a thrift or an electronic identifier. Here is the full table and the logic behind it.
The leading zero is part of the number and must be kept.
21 minus 20 is 1, the same district as 01.
In districts 10 to 12 the thrift first digit is 3.
61 minus 60 is 1. It shows up in processor transactions, not at the foot of a check.
A number listed on the Federal Reserve page of check routing keys.
Multiply the 9 digits by the weights 3, 7, 1, 3, 7, 1, 3, 7, 1 and add them up: the number is valid when the total is a multiple of 10. To find the ninth digit, add only the first 8 products and take 10 minus the remainder after dividing by 10 (0 if the remainder is 0). In 111000025 the first 8 products add up to 3+7+1+0+0+0+0+14 = 25, 5 short of 30, so the ninth digit is 5.
No. According to the Federal Reserve, it indicates the district in which the bank is located. It does not reveal the branch where the account was opened or the holder's address.
The 21 to 32 range is no longer assigned to new institutions, per the public description of the structure, but existing numbers remain in use and valid. That is why the validator accepts these prefixes.
It does not exist today. The Federal Reserve has 12 districts, and the published ranges are 00 to 12, 21 to 32, 61 to 72 and 80. Any validator that accepts 13 is looser than the known specification.
1100-0000-0
| Digit | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
|---|---|---|---|---|---|---|---|---|---|
| Weight | 3 | 7 | 1 | 3 | 7 | 1 | 3 | 7 | 1 |
| Product | 3 | 7 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
3 + 7 + 0 + 0 + 0 + 0 + 0 + 0 + 0 = 10 | 10 mod 10 = 0
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