You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

The answer I give is yes, but what I mean is no. What was the question?

If 21x = 79x, what is the value of x?

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

What Deficiency does the below rebus represent?

VIT_MIN

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

John said, "If yesterday was tomorrow, today would be Friday."

When did John make this statement?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

Find three numbers such that When we multiply three numbers, we will get the prime numbers. The difference between the second and the first number is equal to the third and second.