Page 11 - E book 5

Delta Modern Language Schools

Primary stage Grade 5

Math department

1st term 2024/2025

EX: Find the common factors ad GCF of 12 , 15

Frist way ( listing method)

12 : 12 , 2 , 6 , 3 , 4 , 1
15: 15 , 3 , 5 , 1

Common factors: 1 , 3
G.C.F : 3

Second way ( prime factorization )

12 15

34 35

22

12 = 3 x 2 x 2

15 = 3 x 5

G.C.F = 3

Remark :

If there are no common prime factors , the G.C.F is 1

➢ G.C.F of 7 and 19 is 1
➢ G.C.F of 4 and 7 is 1

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