What is more useful when it is broken?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

Can you find out the total number of triangles in the given figure?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

Can you divide the below-given shape into four equal and identical pieces?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

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?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?