B Nirmala Shastry Solutions for Exercise 7: Riddles

Think of any number. Double it. Multiply the product by $5$. Divide the product by $10$. What do you get?

Tell me who I am
I will give you a clue
You will get me back
If you take me out of twenty two!

Think of any number.
Add $25$ and double your result
Add $40$ and divide by $2$
Take away the number you thought of
You answer is five less than half a century.