Fluency demands more of learners than just the memorisation of a single procedure or collection of facts. It encompasses a mixture of efficiency, accuracy and flexibility. Fluency involves the quick and efficient recall of facts and procedures.
This is an important skill in order for pupils to keep track of sub steps, think strategically and solve problems. When pupils develop their fluency in mathematics, they are then more able to do things without occupying the mind with the low level details that are required; this is usually the result of learning, repetition, and practise.