What is a use of factors and multiples?

Answer 1

I cannot say that nowadays with the use of calculators and computer that we 'need' to figure out the factors of a number in real life. One use I can think of is to splitting the bill among friends. In school, the use would be during an exam, it would be handy to break large numbers into smaller ones when you are asked to simplify a fraction.

One other practical use is approximation. Sometimes I want to check whether my calculator results make sense -- I can use factors and multiples to reduce the numbers to their simplest form and get an approximate answer. Other times, I just need an approximate answer in my head without the benefit of a calculator.