GCF, LCM and fraction sums
Answers are for parents and teachers.
1
Write 20 + 28 with the GCF outside the brackets and find its value.
GCF = 4, so 20 + 28 = 4 × (5 + 7) = 48.
2
Find the LCM of 8 and 20.
40 (8 = 2 × 2 × 2 and 20 = 2 × 2 × 5; LCM = 2 × 2 × 2 × 5 = 40).
3
Add 2/3 + 1/4.
LCM 12: 8/12 + 3/12 = 11/12.
4
Subtract 9/10 − 2/5 and simplify.
LCM 10: 9/10 − 4/10 = 5/10 = 1/2.
5
A juice shop uses 3/4 L of mango juice and 5/6 L of guava juice. How many litres is that? Write a mixed number.
LCM 12: 9/12 + 10/12 = 19/12 = 1 7/12 L.