Seems like pretty much any number you choose is a multiple of 9, and all the multiples of 9 are the exact same gift.. 9,27,36,45,54,63,72,81,99
pick any number you like.. solve that formula, and you'll end up with one of the above.
yeah we've been over this, it's a math trick. look at every single multiple of 9 in the chart. when you do what it asks, you will always result in a multiple of 9.