Sums, differences and products N1.1 Core Plenary A) Find two whole numbers whose product is −4 and whose difference is 4. B) Find two whole numbers whose product is −8 and whose sum is −2. C) Find two whole numbers whose difference is 9 and whose sum is 1. D) Find two whole numbers whose difference is 16 and whose sum is 0. How did you solve the puzzles? Make up and try out some ‘Sums, differences and products’ puzzles for yourself. Preamble These four puzzles, along with any others pupils may construct for themselves, give practice in the number operations with positive and negative numbers, using informal trial and improvement. Try to stimulate discussion about the strategies employed by pupils. Possible content Pencil and paper calculations involving both positive and negative integers, informal trial and improvement. Resources None. Solution/Notes A) −2 and 2 B) −4 and 2 C) −4 and 5 D) −8 and 8 Original Material © Cambridge University Press 2009 Original Material © Cambridge University Press 2009