How many triangles are there on the puzzle below?

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?

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?

What is the largest number you can write with just 3 digits?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

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

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

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

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