How do you do cancellations with large numbers when simplifying fractions? - Answers

This becomes easier with experience and having the ability to recognise that certain numbers are factors of both the numerator and denominator. Until this experience is gained simply try dividing the numerator and denominator by prime numbers of increasing value. (2, 3, 5, 7, 11, 13, 17 etc) Obviously if this division is successful then the fraction can be simplified but this does not necessarily mean further simplification is not possible. Simplification ceases when either the numerator or the denominator becomes a Prime number or has the value 1. This last condition usually applies to just the numerator. All non-prime numbers can be factored into prime numbers so it is only necessary, at this stage, to divide using prime numbers.