If two's company, and three's a crowd, then whats four and five ?

The more you take me, the more you leave me behind.
Who Am I?

Below, you can see three complete equations and one incomplete. Based on the three complete ones, can you complete the incomplete one?

5 $ 4 $ 3 $ 9 = 4215
6 $ 9 $ 2 $ 6 = 3816
4 $ 7 $ 3 $ 3 = 1122
7 $ 2 $ 7 $ 4 = ____

What has many keys but can’t open a single lock?

In a particular village, only two barbershops exist.

The first shop has a handsome barber with a neat haircut who is handsomely dressed in clean clothes and is extremely humble with his body language. The place is clean and looks hygienic.

In the second shop, you can find a barber with shabby clothing. His hairs are weirdly cut and his clothes still have the stains from last night's dinner. The place is not clean as well and reeks a bit.

You visit the village for the first time and decide to get your haircut. Which barbershop will you like to go for that and why?

Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

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

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