What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

Which five letter word can be added at the end of below word to form a
valid word?

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Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Which is the correct shadow of the bird?

Can you find the least possible number such that

If the number is divided by 3, it gives the remainder of 1;
If the number is divided by 4, it gives the remainder of 2;
If the number is divided by 5, it gives the remainder of 3;
If the number is divided by 6, it gives the remainder of 4.

It is always ahead of me yet I can never see it. What is it?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?