Factors, Multiples and Primes: แบบฝึกหัด

Find the highest common factor (HCF) of 18, 42 and 72.

Find the highest common factor (HCF) of 24 and 60.

Which of the following numbers is a prime number?

Which of the following is the lowest common multiple (LCM) of 12, 18, and 30?

Find the least common multiple (LCM) of 15, 20 and 30.

What is the smallest prime number greater than 20?

Determine if 157 is a prime number.

The prime factorization of a number is \( 2^x \cdot 3^2 \cdot 5 \). If the number is 360, find the value of \( x \) and then determine the total number of factors this number has.

Consider the integers 84 and 126.
(a) Express each number as a product of its prime factors in index form.
(b) Find the Highest Common Factor (HCF) and Least Common Multiple (LCM) of 84 and 126.

Consider the numbers 42 and 70.
(a) Express both numbers as products of their prime factors.
(b) Find the Highest Common Factor (HCF) of 42 and 70.