What is the sum of the factors of 21?

To answer this question, we first need to work out the factors of 21. These are the whole numbers which multiply to make 21. We know that 1 multiplies with 21 to make 21, so they are both factors. 2 is not a factor of 21, because we cannot multiply it with another whole number to make 21.3 is a factor of 21, because it multiplies with 7 to make 21. Therefore the factors of 21 are 1, 3, 7 and 21. All that is left to do is to work out the sum of these numbers, that is to add them all up. 21+1 + 3 +7 = 32Therefore, the sum of the factors of 21 is 32. 

Answered by Melissa P. Maths tutor

51037 Views

See similar Maths 11 Plus tutors

Related Maths 11 Plus answers

All answers ▸

Chloe has 3 pieces of wool. One piece is 160mm long, another is 26cm long and the last piece is 0.45m long. What is the total length of wool, in centimetres, that Chloe has?


What is 4/5 of 60?


How many thirds are there in 9?


A sunflower is one hundred and fifty centimetres tall. How tall will it be if its height increases by ten per cent?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences