In the USA, the Common Core Standards in Mathematics for the early grades (K-3) are designed to build on and develop students' number sense as students gain understanding of the structures of addition, subtraction, multiplication and division. It is well understood in teaching circles that subtraction is notoriously more difficult for students than addition. In this article, the authors argue that exploring multiple approaches to subtraction is a critical step in overcoming this difficult transition. They contend that all lessons should support the development of number sense which allows students to think strategically about and compute numbers and better meets the demands of rigorous mathematics instruction outlined in the curricula.