what does the below rebus means?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

Name a key which is hardest to turn.

How many sides does a circle have?

In the figure that has been attached to this question, each digit represents a digit. The similar letters carry the same integer value. Can you expose the original digits?

How could a baby fall out of a twenty-story building onto the ground and live?

O_er_t_o_

Complete the missing letters of the given word.

There is a hypothetical state between the USA and Mexico border 'Tango'.
Here 70 percent of the population have defective eyesight, 75 percent are hard of hearing, 80 percent have Nose trouble and 85 percent suffer from allergies, what percentage (at a minimum) suffer from all four ailments?

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

What does the below image rebus riddle means ?