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?
Age
14 to 16
Challenge level
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