What does this rebus mean?

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Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

Can you find a number that lies one third of the distance between 1/3 and 2/3?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

How many times in a given day, minutes and hour clock comes in a straight line ?

Move four matchsticks to the below square to form three squares?

In a rainy season, one day 3 huge ladies walked under a normal-sized umbrella.
The umbrella is not huge enough to accommodate all 3 ladies yet not a single lady got wet. Why?

One of the leprechaun is missing if you see the two pictures attached to this question. Where did he go? When he comes back, do you know where has he been?