Which tank will fill first?

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?

One day Jenifer meets the Lion and the Tiger in the Forest of Forgetfulness. She knows that the Lion lies on Mondays, Tuesdays, and Wednesdays, and tells the truth on the other days of the week. The Tiger, on the other hand, lies on Thursdays, Fridays, and Saturdays, but tells the truth on the other days of the week. Now they make the following statements to Jenifer:

Lion: Yesterday was one of my lying days.

Tiger: Yesterday was one of my lying days too.

What day is it?

A Man gave one of his sons 10 cents and another son was given 15 cents. What time is it?
Hint: Figure out the relation between time and number, is not so easy..:)

Why is the Hole below a Lock?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

Count the squares in the matchstick puzzle below?

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