RareBillDouble quad
Four of one digit followed by four of another: 55558888. A clean, obvious block pattern that photographs well and sells well.
How rare is it? Exactly 90 of the 100,000,000 possible eight-digit serial numbers are double quads — about 1 in 1,111,111. That figure is counted, not estimated: every possible serial was run through the same engine the RareBill app uses.
How to spot one
Split the serial down the middle. If each half is four identical digits, and the halves differ, it is a double quad.
Example: 55558888 —
check this one in the lookup.
What it is worth
A strong mid-tier find — less than a solid, comfortably above a binary.
Condition matters as much as the pattern. A crisp uncirculated note can be worth many times the same serial in worn condition, which is why RareBill shows value ranges with links to current listings rather than a single number.
Where it sits
Among the sixteen patterns RareBill checks, double quads rank #5 by scarcity.
Only solids, super repeaters, super radars are rarer among the patterns RareBill checks.
Check a serial now
Type any serial into the free lookup and it will tell you every pattern it matches, instantly, in your browser.