what does the below rebus means?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.

What word begins and ends with an E, but has only one letter?

There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

Can you count the number of triangles inside a triangle?

A man always keeps a spare tyre in his car. To make full use of all the five tyres, he changes the tyres in a manner that for a distance of 1, 00,000 km, each of them runs the same distance.

Can you calculate the distance travelled by each tyre on that journey?

Women do it once a year after they turn 19 but men get to do it only once in a lifetime. What is it?