Page 18 - Math Smart - 7

Check My
Understanding

O Use factor trees to find the LCM of the following numbers:
a) 15 and 30 b) 12 and 16 c) 15 and 20 d) 28 and 96 e) 10. 16 and 40

o A business woman goes to New York every 15 days for one day. Another business woman goes
to New York every 24 days, also for one day. Today both of them are in New York.
How many days later will they be in New York on the same day again? Hint: Use a factor tree.

.22 Highest common Factor (HCF)

Example 6

O Find the common factors of 30 and 20.
O What is the highest common factor of 30 and 20?

Answer
You can use a list of the factors of 30 and 20 to find the answer:
Factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30.
Factors of 20 are 1, 2, 4, 5, 10 and 20.
O The common factors of 30 and 20 are 1, 2, 5 and 10.
O The highest common factor of 30 and 20 is 10.

How to use factor trees to find the HCF

Try and Apply!

Chris is making identical flower
- -' AC?'')
arrangements for a party. She has 24
orange flowers, and 16 yellow flowers.
She wants each arrangement to have
the same number of each flower
colour. What is the greatest number
of arrangements that she can make if
every flower is used?
16 24

Factors, Multiples and Primes