Whole numbers: primes, GCF, and LCM

Advanced Math 6 · Unit 1 · gcf-lcm-grade6

gcf-lcm-grade6

Name ______________________________Date ______________

1.
Write $84$ as a product of primes. How many distinct prime factors does it have?
Answer: ______________
2.
Using $84 = 2^2 \cdot 3 \cdot 7$ and $120 = 2^3 \cdot 3 \cdot 5$ , find $\text{GCF}(84, 120)$ .
Answer: ______________
3.
Using $84 = 2^2 \cdot 3 \cdot 7$ and $120 = 2^3 \cdot 3 \cdot 5$ , find $\text{LCM}(84, 120)$ .
Answer: ______________
4.
Two buses leave the depot together at 8:00. Bus A leaves every $12$ minutes and Bus B every $18$ minutes. When do they next leave together?
1. (A)
  8:06
2. (B)
  8:30
3. (C)
  8:36
4. (D)
  11:36
5.
A ribbon $84$ cm long and a ribbon $120$ cm long are each cut into pieces of the same length, as long as possible, with nothing left over. How many pieces are there in total?
1. (A)
  12
2. (B)
  17
3. (C)
  24
4. (D)
  204
5. (E)
  840