math for elementry school teacher
posted by deadlove .
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?

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