Write a formal proof to prove the following conjecture to betrue or false.
If the statement is true, write a formal proof of it. If thestatement is false, provide a counterexample and a slightlymodified statement that is true and write a formal proof of yournew statement.
Conjecture: Let w, x, y, and z be single-digit numbers. The4-digit number wxyz* is divisible by 9 if and only if 9 divides thesum w + x + y + z.
* I don't mean the product of the of these numbers. I mean afour-digit number like 7,235 where w = 7, x = 2, y = 3, and z = 5are the digits.
