Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

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

I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.

John speaks the truth only once a day in a week. Below are a few hints for you:

First: Days are Sunday, Monday and so on.
Second: One day he says, "I lie on Monday and Tuesday".
Third: On the next day, he says, "Today is either Thursday, Saturday or Sunday".
Fourth: On the next day, he says, "I lie on Wednesday and Friday".

Can you identify the day on which he speaks the truth?

What can you catch but never throw?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

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

What Word am I Looking For ?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.