A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

Why is the Hole below a Lock?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

In the image given, you can find several triangles. Can you count them all?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

Rearrange the letters in "new door" to make one word.

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Nor do I know your number.
A: Now I know.

What are the four solutions for this?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?

81 x 9 = 801. What must you do to make the this equation true?