“…The researchers who have evaluated number sense in students from both educational stages have concluded that most students tend to use rules and algorithms when solving number problems (Veloo, 2010;Yang, 2005;Yang et al, 2008). Inadequate number sense skills have also been found in research involving in-service and pre-service primary and secondary school teachers, which highlights the need to address this deficiency as part of their university (Veloo, 2010;Almeida, Bruno y Perdomo-Díaz, 2014, 2016Tsao, 2004;Sengul, 2013;Yang, Reys, & Reys, 2009). These findings have serious implications for classroom instruction, especially if we consider that a limited knowledge of a subject restricts teachers' ability to promote conceptual learning in their students.…”