If you try to zoom out a map using paper in a crafting table, once you hit scale 1:16 or more, the number of paper in the crafting table increases. If you were using a stack of 64 paper, the number of stacked items becomes greater than 64. Once you take the map out of the crafting table, the number reverts to what is should be. Note: This also works with stacks < 64. Stacks of 4 paper will become 8, etc.