What is at the end of a rainbow?

A mathematician couple was having a Frappuccino in Starbucks sitting opposite to each other. Suddenly the guy noticed the text written on the paper in front of them and exclaimed that it was wrong. The girl denied it and said it is appropriate. Both are correct. What is written on the paper?

Replace the question mark with the correct number in the below-given picture?

Buy me, smell me or deliver me, I do not change.

Who am I?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

Two friends were betting. One said to the other, "The coin will be flipped twenty times and each time the coin lands on the head, I will give you $2 and each time it lands on the tale, you will give me $3." After flipping the coin twenty times not a single penny was exchanged among them.

How many times did the coin land on heads?

Can you find out what is missing?

1 3 5
2 4 ?

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

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

What does this below rebus puzzle mean?