Cristina was born in 1888. She just had her 30th birthday today how did that happen?

You are provided with a grid (as shown in the picture). Can you fill the squares with numbers 1-8 in a manner that none of the two consecutive numbers are placed next to each other in any direction (vertically, horizontally or diagonally?)

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?

What does the below mathematical rebus mean?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

Two men play a dice game involving roll of two standard dice. Man X says that a 12 will be rolled first. Man Y says that two consecutive 7s will be rolled first. The men keep rolling until one of them wins.

What is the probability that X will win ?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Can you count the number of triangles in the given figure?