17 is a Prime number because it has only two factors which are itself and one
One mathematical fact about number 23 is that number 23 is an odd number. Another mathematical fact about number 23 is that number 23 is prime number.
it's prime
That's not a "mathematical principle", it is an approximation of the number pi.That's not a "mathematical principle", it is an approximation of the number pi.That's not a "mathematical principle", it is an approximation of the number pi.That's not a "mathematical principle", it is an approximation of the number pi.
Just writing "81" is mathematical enough for my taste. After all, that's a number, and numbers are mathematical.
20 if you divide by 17. 19 if you divide by 16. 18 if you divide by 15, 17 if you divide by 14. And so on. In fact any number from 10 to 99. That is, every two digit number.