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

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

What's the only room from which no one can enter or leave

Outside a massage parlour, there is a board that reads
"I only massage those who do not massage themselves."

Reading the above statement, does the masseur massage himself?

John: "Hi Teacher, What is your favourite movie ?".
Chemistry Teacher: "Indium Cerium Platinum Iodine Oxygen Nitrogen".
Ten seconds later... John replied I got it.

Do you?

How many triangles are there in the picture below?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

At a party, there are five people and a whole round cake lying at the centre of the table. Only four people will make a cut and take their piece and the last one will get the remaining piece on the table. How can they make sure that everyone gets a 1/5th of the piece?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?