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

John buys rice at Rs.60/kg from Britain and then sells them at Rs.5/kg in India. As a result of this, he becomes a millionaire. How come?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Which English verb becomes past tense just by rearranging the letters?

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for only two minutes?

Find the number of squares in the below picture

What number comes next in this sequence:
7 8 5 5 3 4 4 _

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

In a guessing game, five friends had to guess the exact numbers of apples in a covered basket.
Friends guessed 22, 24, 29, 33, and 38, but none of the guesses was correct. The guesses were off by 1, 8, 6, 3, and 8 (in random order).

Can you determine the number of apples in a basket from this information?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?