Recently I was prompted to memorise my debit card number because the particular app that I was using required me to insert it every time I wanted to top up my transport card. This requirement is probably a good thing but it was frustrating to have to retrieve my debit card while out in public, getting my transport card ready for scanning and entering data into my mobile phone.
Getting that debit card number stored in my head would be a big help and so I resolved to do so. The bank's card contains sixteen digits divided into four blocks of four thus:
XXXX - XXXX - XXXX - XXXX
However I didn't find this helpful and ended up grouping them as follows:
XXX - XXX - XXX - XXXX - X - XX
I did this because it helped me to see a pattern in the numbers. To illustrate what I mean, let's generate a random sixteen, bank-type digit number and see what patterns we can see:
7900 - 7950 - 0133 - 9508
An immediate grouping of 790079 is obvious. So we have:
790079 - 50 - 0133 - 9508
A second grouping of 5001 suggests itself because of the similarity of the middle two zero digits in both groups. So now we have:
790079 - 5001 - 33 - 9508
The fact that 3 times 3 equals 9 prompts the next group of 339 so that now we have:
790079 - 5001 - 339 - 508
Remembering to begin with 79 is aided by the fact that 7 + 9 = 16 are there are sixteen digits in the number. The arithmetic digital root of the first block (790079) is 5 so this helps in setting up the first digit of the second block. There are only four digits in the second block and 5 - 4 = 1 which helps in remembering the last digit in the second block. We know that there is a middle 00 in both block. There are only three digits in the third block so that helps in remembering the first digit of the second block. The fourth and final block stands on its own but it is similar to the second block in that both begin with 5 and between the first and last digits there are only zeroes.
That's the way I'd remember that number. Let's try another randomly generated number.
4579 - 4661 - 9790 - 0734
Let's look at the 4 more closely. It can be viewed as 4 = 1 x 2 x 2 and if we add 1 to the 4 we get 5, then add 2 to the 5 to get 7 and 2 to the 7 to get 9, we end up with our first block of 4579. The second block begins with a four as did the first but is followed by six and not a four. However, 45 and 46 are consecutive numbers and we look at 46 reversed (64), we see that 61 is the nearest prime to 64. The next block begins with 97 which is the reverse of the last two digits of the first block (79). If we just include the 9 again, we have an easy to remember palindrome. Thus we have:
4579 - 4661 - 979 - 0 - 0734
I think the 007 would be obvious to everybody that gives us:
4579 - 4661 - 979 - 007 - 34
The remaining 34 connects to the previous 7 because 3 + 4 = 7. The number ends with a four and also starts with a four. That would be my approach but it may be for everybody because not everybody has made a study of numbers like I have and so the connections that I describe would not come easily. Another memory approach is the pinfruit method that I describe in a post titled
Remembering PIN Numbers and also
Time to Remember. See Figures 1 and 2.
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Figure 1 |
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Figure 2 |
Using this method, a sixteen digit number will involve eight images. Thus 7900795001339508 is broken into the doublets 79 - 00 - 79 - 50 - 01 - 33 - 95 - 08 and becomes cup - oasis - cup - heels - suit - mammoth - pillow - sofa. One can form some sort of image from this such as "I dipped my CUP into the OASIS and filled the CUP. I still had my high HEELS and SUIT on and had a MAMMOTH drink after which I put my head on the PILLOW and fell asleep on the SOFA. Here the words cup, oasis, cup, heels, suit, mammoth, pillow and sofa each encode two digits of the sixteen digit word.
It's a matter of choice. I think for digits in excess of twenty that this might be a more robust method and certainly the only choice of very large numbers of digits.
