MYTUTOR SUBJECT ANSWERS

1080 views

What is the highest common factor of 24 and 90?

To find out the highest common factor of two different numbers, first of all we write each number as a product of its primes. 

Here we have

24 = 2 x 2 x 2 x 3 = 2^3 x 3^1

180 = 2 x 2 x 3 x 3 x 5 = 2^2 x 3^2 x 5^1

Now comes the important part. We compare the the prime factors of each number, and take the lower power of the two. So for example, we take out the 2^2 (2 squared) from the 180, because that power is smaller that the one for 24 (where we have 2^3). 

Similarly, we notice that 3^1 is the smaller power of the two cases (we have 3^2 for 180), and so we take out 3^1 (i.e. 3).

Finally, we see that the two numbers share no other prime factors, so now we simply multiply what we have taken out, and that it the highest common factor. i.e.

hcf(24, 180) = 2^2 x 3 = 4 x 3 = 12

And there's our answer. 

Joseph P. GCSE Maths tutor, A Level Maths tutor, GCSE French tutor, U...

1 year ago

Answered by Joseph, a GCSE Maths tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

618 SUBJECT SPECIALISTS

£24 /hr

Daniel K.

Degree: Mathematical and Theoretical Physics (Masters) - Oxford, Merton College University

Subjects offered:Maths, Science+ 5 more

Maths
Science
Physics
Further Mathematics
Chemistry
.MAT.
-Personal Statements-

“Mathematics and Theoretical Physics, University of Oxford. I enjoy sharing my experience and enthusiasm in Maths with those who could do with some help”

£24 /hr

Samuel C.

Degree: Physics (Bachelors) - Durham University

Subjects offered:Maths, Physics+ 2 more

Maths
Physics
Further Mathematics
Chemistry

“Hi, I'm Sam Crawford. I'm studying Maths and Physics at Durham University, with an offer from Cambridge for next year, and I absolutely love both subjects.”

PremiumTimothy N. A Level Design & Technology tutor, GCSE Design & Technolog...
£36 /hr

Timothy N.

Degree: Architecture and Environmental Engineering (Masters) - Nottingham University

Subjects offered:Maths, Physics+ 2 more

Maths
Physics
Design & Technology
-Personal Statements-

“Hi there, I have a passion for helping students achieve, and believe that with my 200+ hours of experience, we will be able to surpass the grades you want!”

About the author

Joseph P.

Currently unavailable: for regular students

Degree: Mathematics (Bachelors) - Warwick University

Subjects offered:Maths, French+ 1 more

Maths
French
.STEP.

“About MeI am a 20 year old mathematics student at the University of Warwick, about to enter my final year. Though I have always enjoyed a range of subjects (from Latin to Music) I have a particular fondness for maths, and have much ...”

You may also like...

Posts by Joseph

What is exactly differentiation?

What is the difference between bon and bien in french?

What is the highest common factor of 24 and 90?

Other GCSE Maths questions

Factorise x^2+7x+10 to find the roots of the equatino x^2+7x+10=0

Factorise x^2 - 8x - 20

Calculate the angle x in the following diagram. The area of the square is 16cm squared and the total area is 36.6cm squared.

Solve the simultaneous equations 3x + 4y = 17 and 4x + y = 14

View GCSE Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok