What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

Pronounced as 1 letter, And written with 3, 2 letters there are, and 2 only in me. I’m double, I’m single, I’m black blue and grey, I’m read from both ends, and the same either way. What am I?

Count the Triangle in the figure given below:

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

Take one out and scratch my head, I am now black but once was red. What am I?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Which letter of the alphabet has the most water?

What does this mean?

CCCCCCC

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?