What four weights can be used to balance from 1 to 30 pounds?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Before Mount Everest was discovered, what was the highest mountain in the world?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

What word is represented by this rebus?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

How is a fly different from a mosquito?

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

What is harder to catch the faster you run?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?