Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

What four weights can be used to balance from 1 to 30 pounds?

Find the next number in the sequence

5 12 24 36 ?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23?

What is greater than gold but cannot be bought. it can never be sold and can earn if its sought. though it can be broken, it can still be fixed. for by birth it can't start nor by death it is ended.what am i?

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?

Which digit occurred maximum times between the number 1 and 1000?

I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.

Six glasses are in a row. The first three are filled with milk and the last three are empty. By moving only one glass, can you arrange them so that the full and the empty glasses alternate?