With the help clues provided in the image, can you find the 5 digit key?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

What occurs twice in a week, once in a year but never in a day?

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

In the image below, can you find the value of an angle(y)

What goes up but never comes down?

What begins with T, ends with T, and has T in it?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

By using all numbers, i.e. 123456789 and subtraction/addition, operators number 100 can be formed in many ways.
Example: 98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100

But if we add a condition use of the number 32 is a must. Then there are limited solutions.
One of such solution is: 9 - 8 + 76 + 54 - 32 + 1 = 100

Can you tell me any other solution?