Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

Prove that the below maths equation is true.

8 + 8 = 91

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

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

You visit a home for specially-abled children on the occasion of Christmas where you meet with 50 children. You have a box of chocolates containing 50 chocolates exactly.

What if you were asked to one chocolate to each child in a manner that one chocolate still remains in the box? Is it possible?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

Solve the mathematical equation in the picture below.

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23?