Peter's Primes
Peter wrote a list of all the numbers that can be formed by changing one digit of the number 200. How many of Peter's numbers are prime?
Problem
Peter wrote a list of all the numbers that can be formed by changing one digit of the number $200$. How many of Peter's numbers are prime?
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.
Student Solutions
Answer: None of them are prime
2 0 __
2 __ 0 none prime
__ 0 0 none prime
201: 2+1=3 multiple of 3
203: 203$\div$7 = 29
207: multiple of 3
209: not 7 again since too close to 209. 209$\div$11 = 19
None are prime