请教一下数学题

xiliuhuang

Q14:

If 1050 – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?

A.      424

B.      433

C.      440

D.     449

E.      467

Q29:

June 25, 1982, fell on a Friday.  On which day of the week did June 25, 1987, fall?  (Note: 1984 was a leap year.)

A.      Sunday

B.      Monday

C.      Tuesday

D.     Wednesday

E.      Thursday

Q25:

A photographer will arrange 6 people of 6 different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row.  The heights of the people within each row must increase from left to right, and each person in the second row must be taller than the person standing in front of him or her.  How many such arrangements of the 6 people are possible?

 

A.      5

B.      6

C.      9

D.     24

E.      36

BruceNornia

Q14: If 1050 – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?   A.      424 B.      433 C.      440 D.     449 E.      467

 

10^50 - 74 = 99999...999926 其中26之前共有48个9 数字总和为：48*9+2+6 = 440

The correct answer is C

BruceNornia

Q29:

June 25, 1982, fell on a Friday.  On which day of the week did June 25, 1987, fall?  (Note: 1984 was a leap year.)

A.      Sunday

B.      Monday

C.      Tuesday

D.     Wednesday

E.      Thursday

 

一个基本的概念是每隔一年(非闰年)那么 相同的月日 星期数往后错1天 比方说 今年1月1日 为周一，那么明年1月1日就是周二（前提是今年不是闰年）

如果中间是闰年 就错两天

 

那么82年6 25是周五，87年6 25 5年中4个平年 1各闰年 所以往后错6天

从而为87年6 25 为周四

 

The Correct Answer is E

BruceNornia

Q25:

A photographer will arrange 6 people of 6 different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row.  The heights of the people within each row must increase from left to right, and each person in the second row must be taller than the person standing in front of him or her.  How many such arrangements of the 6 people are possible?

 

A.      5

B.      6

C.      9

D.     24

E.      36

 

这个题目是5种 之前讨论过很多次，楼主翻下以前的帖子吧

或者自己枚举