You don't need a nested IF to do that. You can use the AND join to set both tests as part of the "IF" test statement. So you get "IF( Test1 AND Test2, Result1, Result2). BOTH Test1 and Test2 must return as true to get result1. On the other hand if either Test1 or Test2 or both return false, then Result2 is the outcome.
NumberField = "X"
OrderField = "Exact Reprint"
MachineField is setup as a calculation with the following formula: IF(NumberField = "X" AND OrderField = "Exact Reprint", 46, "") [If 46 is to be treated as a number then leave it without the quotes, if it is to be treated as text use "46" - quote + 46 + quote - in the formula instead.