Madison County School officials asking for more $

So last year Madison County voters generously approved $40 Million to pay for a new elementary and high school. Now, school officials say, "Oops! We made a big mistake.... could y'all pony up another $16 Mil?" $56 Million is an AWFUL lot of money, but I would be certain that they weren't thinking that it's easier to ask for $40 mil and $16 mil, as opposed to asking for the full $56 Million because that would be devious. I'm sure they made a simple, minor, understandable, $16 million mistake in their efforts to estimate the cost.