Guess the number solution

The pattern is a bit tricky but easy to crack.
Missing number will be 4

The pattern followed is that the sum of two numbers is used to create the upper row.
Example
9+8 = 17 so last digit is 7.
next 8+6 = 14 . Here last digit is 4 and so on.

Hence the correct solution will be 4.

Guess the number

In the below pattern guess the missing number


                                                            ?
                                                        1     3
                                                     7    4     9
                                                  9    8     6    3


Click here for the solution  

Worker Salary Puzzle Solution

We can pay the worker by doing 2 cuts in the chain.

Cut should be such that it divides the chain in the ratio of 4:2:1.

Let us say these pieces are 4x,2x and 1x.

For example - Let us say the chain length is 7 cm. Then make 2 cuts and get 3 pieces of the chain i.e 4 cm,2 cm and 1 cm.

Now the salary will be given to worker as :

Day 1 - Give him 1x cut.

Day 2 - Give him 2x cut and take back 1x cut.

Day 3 - Give him 1x cut.

Day 4 - Give him 4x cut and take back 1x and 2x cut.

Day 5 - Give him 1x cut.

Day 6 - Give him 2x cut and take back 1x cut.

Day 7 - Give him 1x cut.

This way we can pay the worker for 7 days.

Worker Salary Puzzle

You have a metallic chain which has to be paid to a worker for working for 7 days.
You can cut the chain and can pay the worker each day for the work done.
What is the minimum number of cuts required in the chain for paying the worker.

Click here for the solution.

Rotating disc puzzle solution

We can deduce the rotation of the disc with 2 sensors by placing them at an angle of 90 degree.
Let us say we have 2 sensors named A and B.

Now there are two possible initial values of the sensor. Either Black or White.
Let us assume that Black - 0 and White - 1

The disc is rotating clockwise if Sensor A changes to the value of Sensor B and Sensor B becomes Sensor A XOR 1

The disc is rotating counter clockwise if Sensor A changes to the value of Sensor B XOR 1 and Sensor B becomes Sensor A.

This is explained with the below table.

Initial	Clockwise	Counter-Clockwise
A - Black B - Black	A - Black B - White	A - White B - Black
A - Black B - White	A - White B - White	A - Black B - Black
A - White B - Black	A - Black B - Black	A - White B - White
A - White B - White	A - White B - Black	A - Black B - White

Rotating Disc Puzzle

You are given a disc.
One half of the disc is painted black and other half of the disc is white.
You are provided with camera sensors which can predict the color of the disc.
Sensors will indicate the color of the disc.
Find the minimum number of sensors required for to find the direction of the moving disc.

Click here for the solution.