单选题 1．234 1．243 1．324 . . . . . . +4．321 The addition problem above shows four of the 24 different integers that can be formed by using each of the digits 1，2，3，and 4 exactly once in each integer． What is the sum of these 24 integers?
【正确答案】 E
【答案解析】Each digit 1,2, 3, and 4 will appear six times in each of 1,000s place, 100s place, 10s place, and units place. Since 1+2 + 3 + 4= 10,it follows that the sum of the 24 integers is (6)(10)(1,000) + (6)(10)(100) + (6)(10)(10) + (6)(10)(1) = 66,660.The correct answer is E.