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

John can place six large boxes or nine small boxes into a carton.

Can you find out in how many cartons can he place sixty-six boxes in total?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

You have a roll of cloth 1km long. You have a machine which cuts this roll into pieces of 10-meter-long cloth.

How long would it take for the machine to cut the roll if each cut took 4 secs?

How do you go from 98 to 720 using just one letter?

You need to arrange three 7 and mathematical symbols to form number 1?

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

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?

What's a single-digit number with no value?

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

which number am I?