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

How many triangles are there on the puzzle below?

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.

A little girl goes to the store and buys one dozen eggs. As she is going home, all but three break. How many eggs are left unbroken?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Find the value of "?" in the ball picture Riddle below:

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

I am an odd number. Take away a letter and I become even. What number am I?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

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