Whatsapp Forwards

A few days back, my mother got a forwarded message in one of the numerous Whatsapp groups she is part of. I have attached it below

One look at the problem and I was able to conclude that it was nothing but simple algebra at play. Simple algebraic equations twisted around to look like some magic trick.

Most of these forwarded Whatsapp messages that claim to tell your age, read your mind, guess the number you are thinking of etc are nothing but just skillful deception using numbers. Allow me to unravel the mystery behind this.

Wait…Does The Trick Actually Work?

First let us test for ourselves whether the trick works. Suppose the last digit of my mobile number is 3.

1. Take the last digit of your cell number: Let me assume it is 3
2. Multiply that number by 2: 3x2 = 6
3. Add 5 to the number arrived at: 6 + 5 = 11
4. Multiply by 50: 11*50 = 550
5. Add 1770 to the number you got. (Why specifically 1770 you will understand in a little while): 550 + 1770 = 2320
6. Subtract your year of birth from the number so obtained: 2320–1996 = 324
7. You will get a 3 digit number. The first is your cell phone number’s last digit and the other 2 numbers are your age

Yes. 3 is my number’s last digit and 24 is my age. Yes the trick works. Great!!

Now that we have confirmed that the trick works, let us see what is the “magic” behind this.

The Sleight Of Hand

Let us go through the above message step by step

1. Take the last digit of your cell number: We will denote it by x, which can be any single digit number varying from 0 to 9
2. Multiply that number by 2: x on multiplying by 2 becomes 2x
3. Add 5 to the number arrived at: 2x becomes 2x+5
4. Multiply by 50: 50*(2x+5) = 100*x+250
5. Add 1770 to the number you got: 100*x+250+1770 = 100*x+2020(ring a bell??)
6. Subtract your year of birth(let it be y) from the number so obtained: 100*x+(2020-y)
7. You will get a 3 digit number. The first is your cell phone number’s last digit and the other 2 numbers are your age

So, what is the trick here? If you observe, at Step 5, we get a number 100*x+2020. 2020 is the present year. In the next step, you are asked to subtract your year of birth. What do you get when you subtract your year of birth from the present year? You will get your age. That (2020-y) is your age(which is a 2-digit number).

In the above table you can compare the final results of the specific case and the general case. It is clear that, using some clever algebra, your mobile number’s last digit has been cleverly pushed to the hundred’s digit and your age has been brought into the picture(Steps 5&6) without you realizing it.

I hope now you understand that all this is no magic but just skillful deception (similar to a magician’s sleight of hand) using basic number theory and Class 6 algebra.

Can I Also Pull Off This Trick?

Absolutely. Anybody can pull this trick off provided you enjoy playing around with numbers. The only thing you need to remember is that Step 5 is like a common base. Starting from x, you need to reach 100*x+2020. You can add, multiply, divide, do whatever you want. But, you need to reach Step 5. There are 1000’s of ways to do that. Consider the sequence of steps below that I “conjured” up:

1. Think of a number between 0 and 9.
2. Multiply it with 5
3. Add 10 to the above number
4. Multiply with 20
5. Add 1820 to the above number

(Try performing the above mathematical operations. The final result you get will be 100*x+2020)

Like this, you can come up with several scenarios. Just make sure it is not too easy that people can figure it out and neither too difficult that people begin to lose interest.

Once you reach Step 5, you know what to do. Ask them to subtract their age and Voila!!!

Now, you can also create one such “magic” trick, send it as a Whatsapp message in one of your family Whatsapp groups and watch people get enthralled by it

Hope you found this interesting. In one of my next posts, I will discuss a very simple trick which you can try out on unsuspecting 10–12 year olds and watch them get surprised.

Thanks for reading