Use this game to impress your friends by your mathematical ability
By: Roal Mohamed
Tags: Math, Mathematics Education, Cryptography, Mathematics

Use this game to impress your friends by your mathematical ability

Ask your friends to select any positive number, and let him write it in his smartphone calculator without telling you which number he picks. Now ask him to multiply this number by 2, after that let him adding 2 to the results. Tell him to press equal. Then let him multiply the result by 5, and add 5. Tell him to press equal. Finally, let him multiply the result by 10, and add 10. Finally, let him tell you the outcome, and you will blow his mine by giving him in just one second the number he began with. Before I tell you how to do that. Let simplify what we said

He will pick number say X then he will do this

(((X*2+2)*5+5)*10+10))), you must be sure he presses the equal after each + so that the order of operations is kept.

For example, suppose I am your friend

I will write 3 in the calculator, then l do that as you told me 3*2+2=8, then 8*5+5=45, at the end 45*10+10 = 460. The final result is 460. For any positive number I start with and fellow this structure, I will end with number contains 60 at the end (in last two digests) regards less the number. and when you take them, and minus one from the rest you get the number he began with. Here it obvious after crossing 60 out we get 4, and 4–1 is 3.

This true for any positive number regards less the size, if we started with 1 we will get 260, 2 give you 360, 10 get you 1160, …500 give 50160.

Just cross the 60 take-ups one from the rest.

This depends on that any number k will give (k+1)60, where k+1 is number remind after your cross 60 at the two last digits.

Try it yourself by playing with numbers, just don’t forget to press equal between the steps. If your friends did wrong, and give your results different from the formal, think form moment, so he thinks you calculate inside your head. And tell he does something wrong, and let him repeat the operation.

This formula can extend to negative numbers. However, the result for -2 and above will be in this Shape — (k+1)40 and you need to cross 40, subtract two from k+1, for example, -2 give -40, when crossing 40 you get 0, then subtract 2, you get -2, it same for the rest -3 give -140, _4 give -240, -500give -49840 after crossing 40 you get -498 minus 2 you get -500. And so on.

(-1) is a special case following the rules for a positive number, that because you get 60 and then cross it out, 0 this reminds, and then take 1 from 0, you get -1. I think now you can guess that 0 will give you 160.

Therefor by noticing that you use it to figure any number your friends started with.

Let him choose a long number, no problems at all, let him write the outcome in a paper, or on the phone, and he will shock when you telling him the number he began his calculation with.

Other benefits you can get from this game

The game can give some insight into the cryptography theory, which we use to hide our data while sending them throw internet. It is a keystone for all our internet communications. When people send data through the internet, we use a formal depend on number theory to cover the data, the receiver will be the only ones who have the key to figuring out. For example suppose we want to send the number 10, we use this formula (in the real world is considered too easy, and we use complicated formal), and we send the number 1160 instead ( so no will figure out what we send), at the end the recipient get 1160, he will use the key to figure out, which in this case cross the 60 and subtract 1. Ideally, we can send anything because letters can turn to numbers.

As you see this formula is too easy and any we can get the answer in seconds. This will bring us to the second topic, quantum computing, which can do millions of calculation in the seconds theoretical. This ability would allow a quantum computer to break many of the cryptographic systems in use today. Therefore, anyone who has a quantum computer can unravel most of the information sent through the world, which will lead to the end of privacy on the internet.

However, Some scientists debate that quantum computing will generate other methods of cryptographic that can be hard to crack by itself, similar to what going on now with ordinary computers.