find examples that contradict the conclusions of proposition 2.4.10 if and are not coprime (i.e. share a factor greater than ). Proposition 2.4.10 if a and bare not coprime (i.e. share a factor greater than 1). Proposition 2.4.10. Here are two interesting facts about coprime integers a and b: If a cand bc, then abc. If a | bc, then a c. .