What does this rebus mean?

O
N
C
E
TIME

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

How many letters are in the alphabet?

John can eat 27 chocolates in an hour, Jacob can eat 2 chocolates in 10 minutes, and Jolly can eat 7 chocolates in 20 minutes. How long will it take them to share and eat a box of 120 chocolates whilst playing Chess?

Which wheel of car does not rotate when you turn your car right?

You can hear me, but you can't touch or see me.

What am I?

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

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?

what does the below math rebus puzzle mean?