### Brain Teasers

# Cats and Mice

A number of cats got together and decided to kill between them 999919 mice. Every cat killed an equal number of mice. How many cats do you think there were?

There are two conditions:

a) It is not one cat that killed the lot because I have used the word 'Cats'

b) It is not 999919 cats because I have used the word 'mice'.

There are two conditions:

a) It is not one cat that killed the lot because I have used the word 'Cats'

b) It is not 999919 cats because I have used the word 'mice'.

### Answer

The number 999919 cannot be a prime number at first glance. If the problem has only one solution, then this number should have only 2 factors. The factors are 991 and 1009 which are both prime. Since each cat killed more mice than there were cats the answer is clearly that 991 cats killed 1009 mice.Hide Answer Show Answer

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