[Tawa]

I will try to translate the steps, maybe we could all understand what happens.

1. tell em to pick a number between 1 and 10

2. multiply this number by 2

This is actually to pick an even number between 2 and 20.

3. add 5

Odd number between 7 and 25.

4. multiply it by 50 ( i will wait for u while u bring a calculator )

You will get a 50 multiplier{Multiple de 50 , I don't know how to say it in English } between 350 and 1250. And because the numbers from the previous steps are odd, you jump 100 between numbers.

5. If you have already had your birthday this year add 1759
If you haven't, add 1758 .

So we have figured that those numbers are {CurrentYear - 250}, When you add the number you have {between 350 and 1250, with 100 step}, you will have:
{Current Year+(number between 100 and 1000, with 100 step)}

Are you starting to see it?

6. now subtract the four digit year that you were born

When you subtract the four digit year of your birthday, you will get:
You age + number between 100 and 1000{Don't forget the 100 step, so you have 100,200,300,400..., Which is actually TheNumberYouPickedInStep1*100 }

So you get: 2 Digit age, and the 3rd digit on the left is the number you picked in the beginning. Brilliant.