How many sides does a circle have?

What does this mathematical rebus means ?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

Can you find the least possible number such that

If the number is divided by 3, it gives the remainder of 1;
If the number is divided by 4, it gives the remainder of 2;
If the number is divided by 5, it gives the remainder of 3;
If the number is divided by 6, it gives the remainder of 4.

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

You need to move three matchsticks to form three squares. Can you do it?

What famous saying does this rebus mean?

COME SERVED <---
COME SERVED
COME SERVED
COME SERVED
COME SERVED

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