Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Can you find the 09 errors in the picture below?

In order to complete the racing competition, the Mexico racetrack has to submit its top and the most famous three horses to win the competition. Due to an electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the Mexico racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?

What begins with T, ends with T, and has T in it?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

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?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

What does this rebus mean?

O
N
C
E
TIME

Which fur should we be getting from the Lion?