B1. Calculate the greatest common divisor and the least common multiple of the numbers 72 and 168. Use the prime factorization method to assist you.
B1. We factorize the numbers into prime factors $72=2^{3} \cdot 3^{2}$ and $168=2^{3} \cdot 3 \cdot 7$. The greatest common divisor sought is $2^{3} \cdot 3=24$, and the least common multiple is $2^{3} \cdot 3^{2} \cdot 7=504$.

Factorization of the number 72 into prime factors .1 point

Factorization of the number 168 into prime factors 1 point

Writing each number as a product of powers of prime numbers $1+1$ point
Determination and writing of the common divisor ..... 1 point
Determination and writing of the common multiple. . ..... 1 point