Crust also includes 1/4 cup melted butter and 1/4 cup sugar.
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Should be about 2 1/2c unless it means the square, half- crackers, which your numbers indicate. The recipe I use for a 9" pie is 10 whole crackers, 1/4c. butter, 2Tb. sugar, but I think 1/4c. sugar is more usual- I don't like things too sweet.