n errand boy was collecting boxes of cakes for the Summer Fair. He collected boxes from various people in his local village and each box was labelled in Roman Numerals with the number of cakes in the box. By the time the errand boy had collected the last box, he was quite hungry, and really needed to eat at least one cake. Luckily the last box was marked with an underlined XI, meaning there were 11 cakes in it. He had the brain wave of turning the box around and underlining the number again to give the impression there were IX, that is 9 cakes. However, after eating the 2 cakes, he was still hungry. How can he change the number shown on the box again and eat more cakes?


He could add an S to the IX to give the impression there were supposed to be 6 cakes in the box, thus eating 5 cakes in total.

Crossing the Bridge

Four people are on one side of a bridge that they need to cross. It is dark, there are holes in the bridge surface, and they only have one flashlight which must travel with them as they cross. To add to their troubles, the bridge will only support two people at a time.

* Now person #1 can walk cross in 1 minute.
* Person #2 has a limp and can cross in 2 minutes.
* Person #3 has a sprained ankle can cross in 5 minutes.
* Person #4 has a cast on his leg and takes 10 minutes to cross.

No matter how fast a person can cross, he must wait for his companion. If #1 goes with #2, it takes 2 minutes for them to cross.If number #2 goes with #4,it takes them 10 minutes.The flashlight cannot be thrown, instead it must be carried and delivered from person to person. The 4 people are trying to make it across in the fastest possible time to make an important appointment in the next town.

What is the fastest time in minutes for them to cross the bridge?


Trip 1: Person 1 & Person 2 across = 2 min
Trip 2: Person 2 back = 2 min
Trip 3: Person 10 &Person 5 across = 10 min
Trip 4: Person 1 back = 1 min
Trip 5: Person 1 w/ Person 2 = 2 min.
Total 17 minutes.

Lockers Puzzle

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it.The third goes to every third locker and, if it is closed, he opens it, and if it is open,he closes it.The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?


open lockers are perfect squares 1, 4, 9, 16, 25........ they are the only numbers divisible by an odd number of whole numbers.
every factor other than the number's square root is paired up with another.
so these lockers will be "changed" an odd number of times.
which means they will be left open.
All the other numbers are divisible by an even number of factors and will consequently end up closed.

the number of open lockers = the number of perfect squares less than or equal to 1000.
numbers are 1 squared, 2 squared, 3 squared, 4 squared, and so on, up to 31 squared. 32 squared>1000
out of range.
ans is 31

so answer is 31

Microsoft Puzzle

"U2" has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge. You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them.

The flashlight must be walked back and forth, it cannot be thrown, etc.
Each band member walks at a different speed. A pair must walk together at the rate of the slower man's pace:

* Bono: - 1 minute to cross
* Edge: - 2 minutes to cross
* Adam: - 5 minutes to cross
* Larry: - 10 minutes to cross

For example: if Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission.

Notes: There is no trick behind this. It is the simple movement of resources in the appropriate order. There are two known answers to this problem. This is based on a question that Microsoft gives to all prospective employees.

Note: Microsoft expects you to answer this question in under 5 minutes!


* Bono: - 1 minute to cross
* Edge: - 2 minutes to cross
* Adam: - 5 minutes to cross
* Larry: - 10 minutes to cross

Bono and Edge Bono comes back ---(2+1)
Adam and Larry Edge comes back----(10+2)
Edge and Bono over---------------(2)

(2+1)+(10+2)+2= 17 mins

Microsoft, hire me because it took me less then 3 MIns to solve :)

Prisoners puzzle

A prisoner is faced with a decision where he must open one of two doors.
Behind each door is either a lady or a tiger. They may be both tigers,both
ladies or one of each.

If the prisoner opens a door to find a lady he will marry her and if he opens
a door to find a tiger he will be eaten alive.Of course,the prisoner would be
prefer to be married than eaten alive.

Each of the doors has a sign bearing a statement that may be either
true or false.The statement on door one says,"In this room there is a
lady,and in the other room there is a tiger."

The statement on door two says,"In one of these rooms there is lady,
and in one of these rooms there is a tiger."

The prisoner is informed that one of the statements is true and one is

Which door should the Prisoner open?

there are two possibilities

>>statement on door 1 is true and statement on door 2 is false.
but this possibility is not feasible because if it is confirm that door 1 has lady and door 2 has tiger then the statement on door 2 can't be wrong because it states that " In one of these rooms there is lady,
and in one of these rooms there is a tiger."

So this possibilty is not feasible.

>>statement on door 1 is false and statement on door 2 is true.
this possibilty is feasible beacase the true statement says "In one of these rooms there is lady,
and in one of these rooms there is a tiger."
and false one thats on door 1 says "In this room there is a
lady,and in the other room there is a tiger."
now correcting this false statement we get our answer i.e. there is tiger behind door 1 and lady is behind door 2.

Prisoner must open door 2..... but Pray that LADY MUST BE BEAUTIFUL

There r some cows & hens in field.Total no of their legs(legs of cows & hens) is equal to twice their head + 14. how many cows r their in fields


say x cows and y hens

cows have 4 legs, hens have 2
all have 1 head (unless you have beheaded some already )


4x + 2y = 2*(x + y) +14

4x + 2y = 2x + 2y + 14

4x = 2x + 14

2x = 14
x = 7
7 cows.

How many points are there on the globe where, by walking one mile south, one mile east,and one mile north,you reach the place where you started?


If you are on north pole, any direction you take is south.
So you walk south, then east back to north makeing equilateral trangle of 1 mile side. Then yes north pole is one point.

Now assume your are 1.159 miles from south pole.
You walk 1 mile towards south. You are 0.159 mile from south pole. by walking 1 mile east (directions on earth are cirular) you would complete full circle 2*Pi*r (r =0.159) = 1 mile and be back at same spot where you started your east walk. Then 1 mile to north. will take you to the same point you started. (1.159, just example, quick thinking, further calculating, you can get, more accurate).

so this is 2nd point.

now 1 + (0.159)/2) from south pole. In this case after walking south for 1 mile, and then east, you wil complete 2 rounds and be at same place where you started your eastward walk. then 1 mile toward north will take you to same point where you sarted.

so this is 3rd pont.

Like this
1 + (0.159)/3 from south pole.. 4th point
1 + (0.159)/4) frrom south pole ..5th point..


Finding a ball less in weight than other 6 balls outof 7 balls.


There are 7 balls which looks similar in shape. however 6 balls are of same weight and one ball is some what less in weight than other 6 balls.
you have a weighing scale.

how you will find ball with less weight with two scaling attempts ?


1 scaling: -- weight 3 balls against 3 balls
if it weigh's equal it means remaing ball is the smaller one.
if one of the side lower than other then do the second scaling with those 3 balls

2 scalling:
1 against 1.
if equal remaining will be smaller else one of the balls currently weighing is smaller.

25 horses puzzle - find minimum number of races.


Given 25 Horses, each of them runs at different speeds.
one can race max 5 horses at a time.
there is no way to calculate the timings.
What is the minimum number of races needed to find out fastest 3 horses.


1. Divide 25 horses into 5 groups of 5 horses each. Race all groups. we will get 3 fastest from each of the groups.

2. now race fastest 5 horses from each race. this will give 1 fastest horse from all horses. elimiate the last two horses.

3. take 2nd and 3rd horse from last race, 2 and 3 from last from the group to which fastes horse belongs( it may possible that 3 fastes horses may be from same group). take the 2nd fasted horse from the group two which 2nd fastest horse belogs from race in last step.

4. do the race for horses selected in step 3, this will give 2nd and 3rd fastes horse.

IT will take minimum 7 races to find fastest 3 horses.

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