Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

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?

Lifeless eyes on my smiling face and watch your child's sleeping place. In their dreams they hold me tight. What am I?

I am Huge on Sunday and Saturday.
I am small from Tuesday to Thursday.
I do not exist on Monday and Friday.
Who am I?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

With the help clues provided in the image, can you find the 5 digit key?

What's the best place to go shopping in the ocean?

I am not a bull but I have horns.
I am not an ass but I have a pack saddle.
Wherever I go, I leave silver behind me.

Who am I?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?