Double Quad Notes
The first four digits are all identical AND the last four digits are all identical — but the two groups use different digits, creating a striking AAAABBBB pattern.
A Double Quad note has a serial number in which the first four digits are all the same AND the last four digits are all the same — but the two groups use different digits. The result is a striking AAAABBBB pattern. Example: 11112222 (four 1s followed by four 2s).
Why "Double Quad"?
The name refers to two groups of four identical digits ("quads"). Each half is itself a small Solid (all four digits identical within that half), but the two halves use different digits, creating a visually dramatic contrast. A Serial like 77774444 is immediately eye-catching even at a glance.
Relationship to Other Categories
Double Quad notes are also 4 of a Kind notes in the strict sense (they have four of one digit AND four of another). However, the Double Quad category takes precedence because it describes a more specific and visually striking pattern. A Double Quad note is always labeled Double Quad first, then also 4 of a Kind if the platform tracks both.
Rarity
Double Quad notes are rare. For a given pair of digits (like 1 and 2), there is exactly one AAAABBBB serial: 11112222. With 10 possible digits for the first group and 9 possible different digits for the second group, there are 90 possible Double Quad serials in any 100,000,000-note run — roughly 1 in 1,100,000.
Value
Double Quad notes are prized by collectors. Circulated examples typically sell for $150–$500; uncirculated examples can reach $500–$2,000. The most visually striking combinations (particularly 99990000, 11119999, 00001111) command premiums over less distinctive digit combinations.
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More in Fancy Serials: Complete Guide
7 of a Kind Notes
Seven identical digits in a row — the second rarest "of a Kind" category, just one digit away from the legendary Solid.
6 of a Kind Notes (Near Solids)
Six identical digits in an 8-digit serial — also called a "near solid," these are highly sought-after by collectors who can't find a true Solid.
5 of a Kind Notes
Five identical digits in an 8-digit serial — common enough to find in a lifetime of looking, rare enough to be worth keeping.