Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A cricket has 6 legs, a squirrel has 4 legs and a spider has 8 legs.

In a local zoo, it was found that the total number of legs is 612. Also, there are equal number of each of the above animals/insects.

Can you find out how many animals are there in the zoo?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

A network of 20 x 10 squares is given to you.

Can you calculate how many unique squares and rectangles can be formed combining two or more individual squares ?

A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day and a half. How many hens does the farmer need to produce one dozen eggs in six days?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?