Solid serial numbers
A solid has all eight digits identical — 77777777. There are 9 in a run of 99,999,999, which is one note in 11,111,111.
Nine, not ten
Ten digits, ten possible solids — except 00000000 is never issued. A press reaching all zeros produces an error note, which is destroyed and replaced with a star note. So nine.
And in practice, eight
Skip numbering means a block never reaches 99,999,999. The real ceiling is 96,000,000 on $1 through $20 and 99,200,000 on $50 and $100, so 99999999 cannot be printed on a modern note at all. The highest solid that can exist today is 88888888. If you are offered a solid 9 on a modern Federal Reserve Note, that is the end of the conversation.
Solids and near solids
| Pattern | Example | In a run | Odds | Standing |
|---|---|---|---|---|
| Solid All eight digits identical. Only nine exist in a full run. | 77777777 | 9 | 1 in 11,111,111 | Trophy |
| Seven in a row Seven matching digits with the odd one at an end — the cleaner of the two forms. | 07777777 | 180 | 1 in 555,556 | Mid-market |
| Seven of a kind Seven matching digits, odd one in the interior. | 77177777 | 540 | 1 in 185,185 | Mid-market |
| Six of a kind Six matching digits. Common enough that the premium is thin. | 66666612 | 22,680 | 1 in 4,409 | Entry fancy |
What one is worth
Premiums are added to face value rather than multiplied by it, and they fall away fast with handling — these are uncirculated figures. A folded example keeps well under half of this.
| Pattern | $1 note | $20 note | $100 note |
|---|---|---|---|
| Solid | $250 – $3,000 | $475 – $5,400 | $750 – $7,900 |
| Seven in a row | $16 – $90 | $45 – $180 | $140 – $325 |
| Seven of a kind | $16 – $90 | $45 – $180 | $140 – $325 |
| Six of a kind | $4 – $25 | $25 – $65 | $110 – $165 |
Check a serial for collector patterns — the checker tests all 34 patterns at once and reports every one a serial matches, with the odds for each.
Where the odd digit sits
Seven matching digits is a real pattern, and it splits in two. When the odd digit is at either end — 07777777 — the serial still reads as a block of sevens with something in front, and collectors call it seven in a row. There are 180 of those. When the odd digit interrupts the middle — 77177777 — there are 540, three times as many, and it reads as a broken solid rather than a clean one.
Six of a kind is where the premium thins out sharply. At 22,680 per run it is roughly one note in 4,409 — scarce sounding, and common enough that most examples sell for very little over face.
Questions
What is a solid serial number?
A solid has all eight digits the same — 11111111 through 99999999. Collectors also call them solids or repeaters of one digit. There are nine possible, because 00000000 is never issued.
How rare is a solid serial number?
Nine in 99,999,999, or one note in roughly 11.1 million. In practical terms a solid is a note most collectors will never encounter in circulation, and nearly every one that exists is already in a collection.
Is 99999999 a solid?
It is a solid by definition, but it cannot exist on a modern note. Skip numbering caps a block well below 99,999,999 — at 96,000,000 on $1 through $20 and 99,200,000 on $50 and $100 — so the highest printable solid is 88888888. A modern note offered as a solid 9 is not what it claims to be.
What is a near solid?
Seven matching digits with one odd one out. Where the odd digit sits matters: at either end it reads cleanly and collectors call it seven in a row, while an interior break is less desirable. There are 180 of the first and 540 of the second per run.
How much is a solid serial number worth?
A solid on a $1 in uncirculated condition is a four-figure note, and higher denominations run higher. It is one of the few fancy serials where the premium dwarfs the note. Condition still matters enormously — a worn solid is worth a fraction of a crisp one.