考试类型:Mathematics > Standard Multiple Choice
Read the following SAT test question and then click on a button to select your answer.
Seven cards in a pile are numbered 
through 
. One card is drawn. The units digit of the sum of the numbers on the remaining cards is 
. What is the number on the drawn card?
A. 
B. 
C. 
D. 
E. 
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正确答案:A 解析: The sum of the numbers on all seven cards is
|
, or 
. Removing a numbered card reduces the sum of the remaining cards by the number on that card. For example, if the card drawn were numbered 
, then the sum of the remaining cards would be 
, a number whose units digit is 
. Similarly, if the card drawn is numbered 
, then the sum of the numbers on the remaining cards is 
, whose units digit is 
. Therefore, the drawn card was numbered 
.
