Rearrange the letters in "new door" to make one word.

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

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

Before the start of the car race, John and Jacob have the same amount of fuel in their car. With this fuel, John can drive for 4 hours while Jacob can drive five hours.
After a time they realize that the amount of fuel left in John's car is 1/4th of the fuel in Jacob's.

For how long they are racing?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

Which is faster, Heat or Cold ? Explain.

Solve this riddle by finding the odd one out from the rest.

What time is it when an elephant sits on a fence?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10