You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Given that

(78)^9 = 6
And (69)^4 = 11

Can you find out

(99)^2 =?

(Note: This is Logical, not Mathematical)

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

There are forty elephants and they have forty-fore heads. How can this be possible?

Can you find out the remainder when 3^300 is divided by 5?

What occurs twice in a week, once in a year but never in a day?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

What is the probability of choosing the correct answer at random from the options below?

a) 1/4
b) 1/2
c) 1
d) 1/4