What does this mathematical rebus means ?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

What number divided by 4 is the same as that number minus 4?

If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.

Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

Can you count the number of squares in the figure below?

I’m tall when I’m young, and I’m short when I’m old. What am I?

By using 'because' continuously three times, can you make an English statement ?