Numbers are hard to remember because a string of digits has no meaning. Your brain stores "golden retriever" easily and "7305" poorly, because the first connects to things you already know. Every method that works for numbers does the same job: it turns digits into something with structure or meaning. This guide covers five methods, from the simple one you can use today (chunking) to the one memory athletes use for hundreds of digits (the major system). Measure yourself before and after with the free number memory test.
Take the number memory test three times and write down your best score. A number flashes, it disappears, and you type it back; each correct answer adds a digit. Because you see the whole number at once, most people score about the same as their digit span, and sometimes a digit or two higher.
These bands are a rule of thumb, not norms. Compare against your own scores rather than anyone else's.
| Digits reached | What is probably happening |
|---|---|
| 5 to 7 | Holding digits one by one, little or no grouping |
| 8 to 10 | Grouping into chunks, often without noticing |
| 11 to 14 | Deliberate chunking plus rehearsal |
| 15+ | A trained system that gives digits meaning |
Working memory holds about four chunks at a time (Cowan, 2001). If each chunk is one digit, you hold four digits. If each chunk is three digits, you hold twelve. That is the whole trick, and it is why phone numbers are printed as 555-0142 rather than 5550142.
Example: 849302716 becomes 849 · 302 · 716. Three chunks instead of nine digits.
Say each chunk as a single number: "eight forty-nine, three-oh-two, seven sixteen".
Keep chunks the same size. Mixed sizes are harder to replay in order.
On the number memory test, chunk as the number appears, before it vanishes.
Spoken rehearsal is the most durable short-term store for digits. Saying chunks with a beat ("eight-forty-NINE, three-oh-TWO") makes them easier to replay, much as a tune is easier to remember than a list. This is also why the sound in Simon helps: the sequence becomes a melody.
Rehearse quietly under your breath. If you only look at the digits, you rely on a visual trace that fades within seconds.
Look for anything you already know inside the number: years (1969, 2008), ages, times (1145), prices, sports scores, area codes, or patterns such as 2468 and 7777. One meaningful chunk can hold four digits at once.
This is exactly how the student known as SF reached a span of 79 digits in the famous study by Ericsson, Chase and Faloon (1980). He was a runner and recoded digit groups as race times, so 3492 became "3 minutes 49.2 seconds, nearly a world-record mile". The method is personal: use whatever you know well, whether that is football, music or history.
The major system is a phonetic code, developed in the 17th to 19th centuries, that turns each digit into a consonant sound. You then add vowels to make words, and words are far easier to remember than digits.
Vowels and the letters w, h and y carry no value, so you can add them freely. Some examples:
32 = m, n = moon
41 = r, t = rat
91 = p, t = pot
3241 = moon, rat = picture a rat howling at the moon
7591 = k, l, p, t = clipped or "cool pet"
It takes a few weeks to become fluent, and it is too slow for a timed test at first. For PINs, dates and long numbers you need to keep, it is the most powerful method there is. Combine it with a memory palace (placing each image along a familiar route) for long sequences; our guide to memory improvement techniques explains how.
| Digit | Sound | Memory hook |
|---|---|---|
| 0 | s, z | z is the first letter of zero |
| 1 | t, d | t has one downstroke |
| 2 | n | n has two downstrokes |
| 3 | m | m has three downstrokes |
| 4 | r | r is the last sound of four |
| 5 | l | L is the Roman numeral 50 |
| 6 | j, sh, ch, soft g | a j looks like a reversed 6 |
| 7 | k, hard c, hard g | a K can be drawn from two 7s |
| 8 | f, v | a cursive f looks like an 8 |
| 9 | p, b | p is a mirrored 9 |
For a number you need to keep, such as a passport number or a bank sort code, test yourself rather than rereading it. Write it from memory after an hour, then the next day, then a few days later. Our guide on how to improve memory covers the same approach for everything else you want to keep. Spaced retrieval is one of the best-supported learning methods in the research literature (Dunlosky and colleagues, 2013).
Two runs of the number memory test, chunking in threes.
Two runs of the digit span test forward, saying chunks aloud.
One run of Number Sequence, where digits arrive one at a time and order matters more.
Learn three new major-system words for numbers from 00 to 99.
Write your best scores down and compare them weekly.
Be realistic about what this changes. Your scores on these tests will rise, and you will get better at remembering numbers you choose to remember. Research on memory training finds that the skill stays fairly specific: getting better at digits does not make you better at remembering names (Melby-Lervåg and colleagues, 2016).
Cowan, N. (2001). The magical number 4 in short-term memory. Behavioral and Brain Sciences.
Ericsson, K. A., Chase, W. G., & Faloon, S. (1980). Acquisition of a memory skill. Science.
Dunlosky, J., et al. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest.
Melby-Lervåg, M., Redick, T. S., & Hulme, C. (2016). Working memory training does not improve performance on measures of far transfer. Perspectives on Psychological Science.
Chunking. Split the number into groups of three or four digits and say each group as one number, like a phone number. You go from holding many digits to holding a few chunks.
Most adults hold about 7 digits in order, give or take two. With deliberate chunking many people reach 10 to 12.
A phonetic code that turns each digit into a consonant sound (1 = t or d, 2 = n, 3 = m and so on). You add vowels to make words, so 32 becomes moon, and remember the words instead of the digits.
They use systems such as the major system or a person-action-object code to turn digits into vivid images, then place those images along a mental route. It is a learned skill, not an unusually large memory.
It improves your score on that test and your skill at holding numbers. Benefits to other kinds of memory are small, so use it as practice for numbers rather than a general memory cure.
Start with chunking today, add rhythm and meaning, and learn the major system if you want to keep long numbers for good. Measure the change with the number memory test and the digit span test, and you will see your scores climb within a week.