# math

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?
3. ### PROBLEM SOLVING IN MATHEMATICS

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