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, which is 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, so these are uncirculated figures. A folded example keeps well under half of this.
| Pattern | $1 note | $20 note | $100 note |
|---|---|---|---|
| Solid | $250 to $3,000 | $475 to $5,400 | $750 to $7,900 |
| Seven in a row | $16 to $90 | $45 to $180 | $140 to $325 |
| Seven of a kind | $16 to $90 | $45 to $180 | $140 to $325 |
| Six of a kind | $4 to $25 | $25 to $65 | $110 to $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, as in 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, as in 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, and a worn solid is worth a fraction of a crisp one.