posted by .

the sum of the digits of a two digit prime number is substracted from the number. prove that the difference cannot be a prime number.

  • math -

    adding the digits produces a result that is the remainder when the number is divided by 9.

    So, assuming that the prime number p = 9m+n
    the sum of the digits is also n

    so, p-n = 9m, not a prime

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math Prime Numbers

    Grade 7 question: I am a two-digit prime number I am one less than a multiple of 10 If you add 30 to me you get another prime number Who am I _________?
  2. 2nd grade

    The sum of my ones digit and tens digit is 10. My tens digit is les than my ones digit and both my digits are prime. i am a prime number. what number am i?

    there are two prime numbers between 100 and 199 such that the ten digits is a prime number, the ones digit is a prime number and the tens and ones digits taken together are a 2 digit prime number. find the sum of these 2 prime number.
  4. math

    I am a 4 digit number greater than 9,000 my omes digit is 3 and my hundreds digit is the smallest prime number greater than 5 the sum of my digits is 20. What number am i?
  5. math

    I am a prime number. I am less than 40. I am 1 more than a multiple of 5. What number am I?
  6. math

    Get the number right. *None of the digits repeat. *It is between 20,000 and 77,777 *The digit in the thousands place is 3 times the digit in the ten thousands place *The ones digit is a prime number *The hundred digit is half the sum …
  7. Math

    What are 2 prime numbers between 100-199 such that the tens digit is a prime number, the ones digit is a prime number, and the tens and ones digit taken together are 2 digit prime number.
  8. Maths

    I am a three-digit number. I am divisible by 6. My middle digit is a prime number. The sum of my digit is 9. I am between 400 and 500. My digits are descending order. What number am I?
  9. math

    Neelesh is fond of playing number games. Once when his friends were present he challenged them. He said that he has thought of a five-digit number and anyone who guesses it correctly can use his cycle for a full day. ‘To help you,’ …
  10. Math

    What is my number? 1.My number is a perfect square 2.The only prime number in it's prime factorization is 2 3.My number is a factor of 32 4. The sum of it's digits is odd.

More Similar Questions