what does the below math rebus puzzle mean?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.

What can a student say to prevent his being expelled from school?

What has many teeth, but cannot bite?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

They are three errirs in this question. Can you find them?

What does this rebus mean?

O
N
C
E
TIME

There are three boxes of different sizes with three cupcakes inside each of the boxes in Christina's kitchen. At night her daughter wakes up and goes to the kitchen. She opens a box and eats all three cakes.

But in the morning Christina finds out that each box still had three cupcakes. How?

You are stuck on an island where you have nothing. You find four pieces of paper somewhere on the island. What will be your strategy to escape from the island safely?

PS: No other resource is available to you on the island, neither can you build anything.