Binary Digits training: the 30‑minute binary numbers event
Thirty minutes to memorise as many 0s and 1s as you can, then an hour to write them back. Standard mode is the World Memory Championship format: a 9,000-digit sheet in rows of 30, scored row by row under the World Memory Sports Council rules — blanks marked as zeros included.
- Memorise
- 30 min
- Recall
- 60 min
- World level
- Sheet
- 9,000
- digits · rows of 30
- Trials
- 1
- World record
- 7,485
- digits · Guinness, 2019
Start a drill
The official Binary Numbers format
Binary digits are computer-generated and presented in rows of 30 digits, 25 rows to a page — 750 digits per page. The rulebook sets the number of digits at the current world record plus 20%. Timings depend on the level of the competition:
| Level | Memorise | Recall |
|---|---|---|
| National | 5 min | 15 min |
| International | 30 min | 60 min |
| World | 30 min | 60 min |
Standard mode runs the World format. With a record of 7,485, plus 20% is 8,982 digits, which rounds up to whole rows of 30: 9,000 digits on 12 pages. The sheet is paged like the paper original, and recall carries straight on from one page to the next. For the National format, set up a Custom run with 5 and 15 minutes.
How Binary Numbers is scored
The scoring mirrors the decimal numbers events on rows of 30. These are the WMSC rules, with the examples the rulebook uses:
- 30A complete row, all 30 correctFull marks for the row.
- 15A complete row with one mistakeA wrong digit, including a blank where a 1 belongs.
- 0Two or more mistakes in a rowMissing digits count here too.
- 0A missing rowNo penalty for rows you skip.
- 20Last row: 20 digits recalled, all correctAn incomplete last row scores the digits recalled.
- 10Last row: 19 recalled, one mistakeHalf of 19 is 9.5, rounded up.
How to memorise binary digits
Holding thousands of raw 0s and 1s isn't realistic. The practical approach is to convert binary into something you already have images for. Three binary digits have exactly eight patterns, so every group of three reads as one digit from 0 to 7:
| Binary | 000 | 001 | 010 | 011 | 100 | 101 | 110 | 111 |
|---|---|---|---|---|---|---|---|---|
| Digit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
- Six digits, one image. Two groups of three give a two-digit number from 00 to 77, and a Major System already has an image for each. A row of 30 becomes five images; a full page, 125.
- Bigger chunks, bigger system. Grouping more digits per image means fewer images per row but more to learn: 6 binary digits have 64 patterns, 9 have 512, and 10 have 1,024.
- Align images with rows. Rows of 30 divide evenly into groups of 3, 6 and 10, so a lost image never pushes the rest of the row out of place. Place them along a memory palace route with a fixed number of loci per row.
- Stop your last row where your confidence stops. Twenty sure digits score 20; padding the row with guesses will probably add a second mistake and score 0.
For choosing a digit system and building journeys, see How to memorise binary numbers.
Binary Numbers FAQ
What is Binary Numbers at the World Memory Championships?
Binary Numbers is the discipline where competitors commit to memory as many binary digits (0s and 1s) as possible, presented in rows of 30, and write them back in order. At International and World level there are 30 minutes to memorise and 60 minutes to recall.
What is the world record for binary digits memorised in 30 minutes?
Guinness World Records lists 7,485 binary digits, memorised by Ryu Song I of the DPRK at the 2019 World Memory Championships in Wuhan, China.
How is Binary Numbers scored?
Row by row. A complete row of 30 recalled correctly scores 30, a row with a single mistake (a missing digit counts) scores 15, and a row with two or more mistakes scores 0. There is no penalty for missing rows. In the last row only, an incomplete row scores the digits recalled if all are correct, or half of them rounded up with one mistake.
Do I have to write the zeros in Binary Numbers?
No. The rulebook lets competitors leave blanks instead of writing zeros, and all blanks are marked as zeros unless the end of a row is indicated. In this drill a blank inside your recall is marked as 0 in the same way.
How does the marker know where my binary recall ends?
On paper you mark the end of your last row, for example with 'E' or a line. If you don't, recall is assumed to end after the last 1 in that row. In this drill the last digit you type marks the end, so if your final row ends in zeros, type them.
How long is the recall period?
60 minutes at International and World level, after a 30-minute memorisation. National competitions run a shorter format: 5 minutes to memorise and 15 to recall.
How are ties broken in Binary Numbers?
By decision points: one point for every correctly positioned binary digit in the rows a competitor attempted but scored 0 for. The competitor with the most decision points wins.
How do you memorise binary digits?
By grouping them. Three binary digits have eight possible patterns, so each group of three can be read as one digit from 0 to 7, and a group of six becomes a two-digit number that an existing number system such as the Major System already has an image for. A row of 30 is then five images.
Keep training
Sources
- World Memory Sports Council rulebook — Binary Numbers (format, recall and scoring)
- Guinness World Records — most binary digits memorised in 30 minutes
Not affiliated with the World Memory Sports Council.