首页
登录
职称英语
A certain online form requires a 2-digit code for the day of the month to be ent
A certain online form requires a 2-digit code for the day of the month to be ent
游客
2024-01-13
56
管理
问题
A certain online form requires a 2-digit code for the day of the month to be entered into one of its fields such as 04 for the 4th day of the month.The code is valid if it is 01,02,03…31 and not valid otherwise. The transpose of a code xy is yx.For example,40 is the transpose of 04.If N is the number of valid codes having a transpose that is not valid,what is the value of N?
选项
A、12
B、13
C、18
D、19
E、20
答案
D
解析
It will be quicker to count the number of valid codes whose transposes are valid codes, and then subtract the result from 31 (the number of valid codes) to obtain the value of N.
Three such codes begin with 0: 01,02,03. The rest are such that their transposes are invalid codes.
Four such codes begin with 1:10,11,12,13. The rest are such that their transposes are invalid codes.
Three such codes begin with 2:20,21,22. The rest are such that their transposes are invalid codes.
Two such codes begin with 3: 30,31. The rest are invalid codes.
Therefore, the total number of valid codes whose transposes are valid codes is 3 + 4 + 3 + 2 =12, and hence the total number of valid codes whose transposes are not valid is 31 - 12 = 19.
The correct answer is D.
转载请注明原文地址:https://tihaiku.com/zcyy/3360051.html
相关试题推荐
Inasecondhandbookshop,Billycameacrossabookwhichhethoughtwascertain
Nomatterwhoyouareorwhereyoucomefrom,onethingiscertain:youarea
Nomatterwhoyouareorwhereyoucomefrom,onethingiscertain:youarea
Customer:______Receptionist:Certainly,doyouhaveareservation?Customer:
Understandingthistransitionrequiresalookatthetwo-sidedconnectionbe
Infact,manystudiesindicatethatafteracertainpoint,anyone’sproductivity
Canonlineeducationeverbeeducationoftheverybestsort?NotlongagoI
Ourpreferencesforcertaincolorsare______accordingtothepassage.[br]Whi
Ourpreferencesforcertaincolorsare______accordingtothepassage.[br]If
Thedegree______youmaintainyourmentalhealthmaydependoncertainsimpleenv
随机试题
Whetheryoukeepallthereceiptsinashoeboxoruseonlinebanking,youshoul
SmithsoldA(mostof)hisB(belongings).HehashardlyC(nothing)leftD(in)the
BadInvestmentTakeitfromabusinessman:TheWar
Itishightimethatthisargument(put)______anendto.wereput本题测试的是虚拟语气的用法。
Thesestatisticsonthethirdpageis______oftheeconomicgrowthofourcount
高等教育的社会功能
新课程改革的具体目标规定要改变课程过于集中的状况,实行__________、地方
外部欺诈事件是指()。A.故意骗取、盗用财产或违反监管规章、法律或公司政策导
违反从业人员职业操守的人员,()。 A.可能受到公众谴责,但尚无法进行实质性
动作技能形成过程的第三阶段是( )A.联结阶段 B.自动化阶段 C.认知阶
最新回复
(
0
)