Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What number divided by 4 is the same as that number minus 4?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Three friends decide to distribute the soda cans they had among them. When all of them had drunk four cans each, the total number of cans that remained was equal to the cans each one of them had after they had divided the cans.

Can you calculate the total number of cans before distribution?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

Replace the question mark with the correct number in below Picture:

Find out the missing number in the picture attached: