Why is it important to memorize multiplication tables?
There is a very simple and important reason why children, and everyone else, should memorize basic multiplication tables.
A great deal of life involves making reasonably quick and reasonably precise decisions with data.
By Ontario Ministry of Education Mathematics Curriculum Guidelines:

Multiplication Table PDF Printable version 
Not knowing their multiplication tables can really slow children’s mathematical progress once they get to school after Grade 3. Not only multiplication questions also… 
