问一道GMAT数学题!Jerome wrote each of the integers 1 through 20,inclusive,on a separate index card.He placed the cards in a box,then drew cards one at a time randomly from the box,without returning the cards he had already drawn to the box.In order to ensure that the sum of all te cards he drew was even,how many card did Jerome have to draw?
问题描述：
问一道GMAT数学题!
Jerome wrote each of the integers 1 through 20,inclusive,on a separate index card.He placed the cards in a box,then drew cards one at a time randomly from the box,without returning the cards he had already drawn to the box.In order to ensure that the sum of all te cards he drew was even,how many card did Jerome have to draw?
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