There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

What common phrase is represented by the below lines

Easy going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Medium going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Tough going:
Weak, 'I can't do it, I'm staying!'
Tough, 'Let's get going.'

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

How many points are there on the globe where, by walking one mile south, then one mile east and then one mile north, you would reach the place where you started?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

A man died, leaving $10,000,000 for his widow, 5 sons and 4 daughters. Each daughter received an equal amount, each son received twice as much as a daughter, and the widow received three times as much as a son.

How much did the widow receive?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

How many sides does a circle have?