What does this rebus mean?

O
N
C
E
TIME

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

Which is Odd One Out and why?

4377

3954

9862

8454

9831

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

John bought a new car. He has a habit of eating ice cream from a particular ice cream shop while returning home from office. Whenever, he eats strawberry ice cream, he faces no problem. But whenever, he eats chocolate ice cream, the car starts giving problem. At first, he thinks, it is just a co-incidence but when this awkward incident happens for 3-4 times, he reports this problem to the company.

The mechanic of the company checks but finds no problem at all. The next day, when he stops by to eat chocolate ice cream, the car again starts giving problem.

Can you find the possible reason?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

I am an odd number. Take away a letter and I become even. What number am I?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

A police officer was passing by when he saw a guy hiding. He walked up to him and genially asked, "What is your name?"

"Shut up!" the boy responded.

"Where are your manners?" asked the outraged police officer.

"Up that tree," said the boy discourteously, directing to a neighbouring tree.

You're looking for trouble, aren't you?" said the police officer.

"No, trouble is looking for me!" the boy answered solemnly.

Why is the boy behaving like this?