Anusha said:Here's the proof.
Say the number you imagined was XY (i.e. if X=4 and Y=3, XY=43).
But if you write it mathematically, it's X*10+Y (in the previous example, 4*10+3 = 43, see?)
Now it asks you to add the two digits ==> (X+Y)
Now let's substract it from X*10+Y==>
X * 10 + Y - (X + Y)
=X * 10 + Y - X - Y
=X * 9 ==> is always a multiple of 9.
The answer is always a multiple of 9.
Now you get it?
yup...it workd this time..lolzz....


How did he know that