On May 7, 2023, bitnox wrote:
I memorized all the 2 digit squares squared . now I in the process of memorizing the multiplication table of 2 digit numbers (11-99)

On May 26, 2023, Micha-el wrote:
The book, "Dead Reckoning: Calculating Without Instruments" can be found on Amazon and will help with some of the stated calculations. The website, https://www.ludism.org/mentat/HomePage has some good memory systems.
Regards,
Barry

On May 22, 2023, saxonia wrote:

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On May 7, 2023, bitnox wrote:
I memorized all the 2 digit squares squared . now I in the process of memorizing the multiplication table of 2 digit numbers (11-99)

This is not something that should be memorized. Train to calculate it quickly instead. Honestly, it's less difficult!

On Jun 2, 2023, bitnox wrote:

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On May 26, 2023, Micha-el wrote:
The book, "Dead Reckoning: Calculating Without Instruments" can be found on Amazon and will help with some of the stated calculations. The website, https://www.ludism.org/mentat/HomePage has some good memory systems.
Regards,
Barry

thanks, I will check the memory system on this

On Jun 3, 2023, FrankFindley wrote:
Interesting challenge you have embarked on.

It is very hard to present squares above six digits because calculators run out of digits on their displays. And that is how this type of mental math feat is typically presented, as a time challenge vs. someone with a calculator.

Because you have already memorized the squares of two digits, you are already set to present a fantastic, instantaneous six digit square as a grand finale. All it takes is a little trickery.

Here is my method. Use a transparent f______ b__. In one side have pieces of folded paper with two digit combinations (that is 10 to 99). In the other have multiple slips all with 00 on them. Have three different spectators each pick a slip. Spectator 1 and 3 choose from the 10 to 99 side. Spectator 2 chooses 00. Then have them each write their digits in order on a whiteboard without you and a fourth spectator seeing it. The fourth spectator has a calculator and is going to race you. You will be able to write out the square immediately upon seeing the six digit number they constructed.

The number they create will be in the form of AB00CD. This is a simplified case for six digit squaring. It becomes AB^2 & 2*AB*CD & CD^2 where the '&' symbol represents a concatenation.

For example, say the constructed number is 180065, then:

18^2 = 324
2*18*65 = 2340
65^2 = 4225

so the square is: 324 & 2340 & 4225 = 32,423,404,225

With this method, you will be able to begin writing the answer instantaneously and will probably have the result on the board before the person has it keyed into their calculator. They then will catch up to you and confirm you have the correct answer.

Just by mixing in this little bit of additional magic method, you can start performing this right now. Then when you achieve your goal of memorizing the 3+ digit squares, you can drop the added subterfuge. However, I doubt even with the memorization of the longer squares that you will be able to do it as quickly as the method just described. The addition of the numbers in the 'legit' way takes much longer than the concatenation. So the method described likely produces better theater.

In any case, starting to perform with this method will build up your calculation speed as you have to do the 2*AB*CD bit. Depending on how you do mental calculations, this may be best done in two parts: 2*AB=2AB and 2AB*CD.

Well, if nothing else, I hope this provides a different perspective on performing these larger squares calculations.

On Jun 2, 2023, bitnox wrote:
depend on what is your goal, on speed memory win, my record is to tell 38 2 digit squares in 30 seconds, write 36 2 digit squares in 30 seconds, type 21 2 digit squares in 30 seconds, and tell the first 14 squares , 9 1 digit squares and 5 2 digit squares , 30 digits in 4 seconds, I don't think this speed is possible with calculation, second of all, let's say I will go to level that I can calculate it, its sound strange : someone that can calculate but don't remember the answers, I think the small things have to memorize, and the big things have to calculate and get aids from the small things, its also depend on the person, I have an excelent born memory, I don't have a trained memory, but its look like a trained one because its very good born,

On Jun 3, 2023, saxonia wrote:

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On Jun 2, 2023, bitnox wrote:
depend on what is your goal, on speed memory win, my record is to tell 38 2 digit squares in 30 seconds, write 36 2 digit squares in 30 seconds, type 21 2 digit squares in 30 seconds, and tell the first 14 squares , 9 1 digit squares and 5 2 digit squares , 30 digits in 4 seconds, I don't think this speed is possible with calculation, second of all, let's say I will go to level that I can calculate it, its sound strange : someone that can calculate but don't remember the answers, I think the small things have to memorize, and the big things have to calculate and get aids from the small things, its also depend on the person, I have an excelent born memory, I don't have a trained memory, but its look like a trained one because its very good born,

Well, I happen to be the organizer of the Mental Calculation World Cup, and I can tell you that it IS possible to calculate so quickly (just have a look at "multiplication" at https://www.recordholders.org/en/list/mental-calculation-rankings.html).
Please do not get me wrong - I absolutely agree that it is important to know a lot of calculation results by heart. But ideally this knowledge should come from repeated practice, not from learning and mnemotechnics. So first, figure out where shortcuts (binomial theorem, Vedic math sutras, etc.) can be helpful - and regard the need to learn a two-digit multiplication as the last option.

I can also strongly recommend Doerfler's book as well as The Mental Calculators' Handbook (https://amzn.to/3N8SRfw).

On Jun 5, 2023, FrankFindley wrote:
It really is the addition of the product parts which ramps up the difficulty. Just remembering the product parts is a challenge. That's where the memory mnemonics can come in handy. Watching an experienced mathemagic performer like Arthur Benjamin talk through it is really something to behold.