Question

Mr. Mathemagician asks you to pick any whole number. Add 10. Multiply the result
by 4. Add 200. Divide by 4. Subtract your original number. Mr. Mathemagician says,
“You’re final result is 60!” Explain Mr. Mathemagician’s trick?

Answer 1

x =original number


Mathematical operations:


Add 10 :

x + 10

Multiply the result by 4 :

( x + 10 ) * 4

Add 200 :

( x + 10 ) * 4 + 200

Divide by 4 :

[ ( x + 10 ) * 4 + 200 ] / 4

Subtract your original number :

[ ( ( x + 10 ) * 4 + 200 ) / 4] - x



Equation is:

[ ( ( x + 10 ) * 4 + 200 ) / 4 ) ] - x =

= ( x + 10 ) * 4 / 4 + 200 / 4 - x =

x + 10 + 50 - x = 60