What is the longest word in the dictionary?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

Here is a conversation between a couple who both are software professionals.

Husband: Hey! What is your date of birth?
Wife Replied Angrily: It is 591062400
Husband after doing some calculations replied, "Got It".

What is the DOB of the wife?

Can you place six X (crosses) in below board without making three in a row in any way ?

I am the largest in my family of fifty.
The youngest of our family lives separately from the rest of the family and so do I.
I am regarded as harsh and tough.
I am so large, you cut me in two equal halves,
each half would still be larger than the second largest member of the family.
Who am I?

Find the value of "?" in the ball picture Riddle below:

why number 8549176320 is one of a kind?

I am a five-letter word and people eat me. If you remove the first letter I become an energy form. If you remove the first two letters, I am needed to live. Scramble the last three letters and I am a drink. What word am I?