Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

A river should be crossed by a father, a mother and their two sons and two daughters.
There are some rules that should be followed while crossing the river. There can be only two people in the raft while crossing. The daughters cannot be with their father unless there is the presence of the mother. The sons cannot be with their mothers unless the father is present. Unless the guard is on the board, the criminals cannot be with any of the family members. Only the adults like the father, the guard, and the mother knows to use the raft.

How will they cross the river?

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

You Throw The Outside, Cook The Inside
Eat The Outside, Throw The Inside.

What Is It?

Suppose you are sitting in an interview and the interviewee asks you an aptitude question.

You have three buckets with a capacity of 4 litres, 8 litres and 10 litres and you have a large tank of water. Now you have to measure 3 litres of water precisely using those buckets. How will you do it?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

Prove that the below maths equation is true.

8 + 8 = 91

Why do we preferably have round manhole covers and not square ones?