NumberThink is a learning aid for the Major System, a well-known technique for remembering numbers by associating them with words.

In the Major System, each digit of a number is associated with a sound (not a letter). By combining the sounds to form words, you just need to remember the words to remember the number.

Tap the star button (you have to close this screen first) to see a list of which sounds are associated with each number.

Some sounds are not associated with numbers (a, e, i, o, u and w) so these are used to help form words.

For example, if you want to remember the number 91, you could simply remember the word "bat", since "b" is associated with 9 and "t" is associated with 1, and "a" isn't associated with a number. You could also remember the word "bet" since "e" is also not associated with a number.

NumberThink helps you learn the Major System in two ways:

1. To help you learn, tap the Teach button and then enter a number to see what the word is.

2. To test your knowledge, tap the Quiz button and then enter the number for the word or phrase shown.

A common use of the Major System is to use it to create a set of specific "peg" words for all the numbers from 1 to 100. This can make it easier to build a phrase for particular number since you always use the same set of peg words. You can customize the list of Peg Words by tapping the gear button (you have to close this screen first).

What's New

Version 5.0

We've rewritten the app from scratch to be modern with a great new look.

Ratings and Reviews

Great update

Ipod and Imac user

This is a great app! I really appreciate the fact that you incorporated the "peg" system into the "major" system and allow your users choose the peg words. The peg system is the workhorse of the major system. I've used it in college to memorize important concepts and I use it in life to memorize every day lists.

For those new to mnemonics, the major system ties a unique sound to each of the ten digits ("s" or "z" to zero; "t" or "d" to one...). So most words can be tied back to a number. (In our example, "daisy" would be ten - 1 'd', 0 's' - the sound 'a' and 'y' don't count).

This update allows you tie "peg" words to numbers 0 through 99. My peg word for 6 is shoe. (The sound for 6 is 'ch' or 'sh'). Let's say I want to memorize the Periodic Table. Carbon has an atomic number of six. I picture in my mind a shoe made up entirely of Carbon. I have my link and my memory.

This update allows the user to set up and practice peg words. It explains the major system, and puts everything into an easy to use program that can be used to memorize peg words and explore mnemonics in a way that the user will find very useful.

Great update. Thank you!

Previous version was better

Brit Rock Music Junkie

I love this app and frequently refer to it. My only complaint is that it no longer has the list of the classic peg words for numbers 0-100. I used to be able to modify the default peg words to my liking or choose to have them generated from the provided data base. Where did this feature go? Or am I missing something?



I work in the hospital and have about 40 phone numbers I'm tired of looking up. Quiz mode in this app has accelerated my learning of the major system and I no longer have a problem remembering these numbers.


Nosleep Software
13.8 MB
Requires iOS 10.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2017 NoSleep Software LLC


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    With Family Sharing set up, up to six family members can use this app.

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