PRIME & COMPOSITE
Is 37 prime or composite?
Prime
List the common factors of 8 and 12.
1, 2, 4
Is 3/20 closer to 0, ½, or 1?
0
What is the LCM of 4 and 6?
12
9 ÷ 2 = ? (Write in mixed number form)
4½
Give all composite numbers between 20 and 25.
21, 22, 24
What is the GCF of 18 and 24?
6
Write an equivalent fraction to 2/3.
4/6, 6/9, 8/12 …
List the first 3 common multiples of 3 and 5.
15, 30, 45
If 23 kids get into cars that hold 4 each, how many cars are needed?
Round up → 6 cars
What is the prime factorization of 28?
22 x 7
What is the GCF of 36 and 54?
18
Is 9/16 closer to 0, ½, or 1?
Closer to ½
What is the LCM of 8 and 12?
24
15 ÷ 7 = ?
2 1/7
True or False: 51 is composite.
true (51 = 3 x 17)
What is the greatest common factor of 15, 20, and 35?
5
Which is larger: 5/12 or 3/7?
5/12 ≈ 0.416
3/7 ≈ 0.428
→ 3/7 is larger
What is the smallest number that is a multiple of both 9 and 15?
45
Tanner buys notebooks. Each costs $3. If he has $20, how many can he buy?
6 notebooks (round down)
A number has exactly three positive factors. Give one possible number and explain why.
Any perfect square of a prime → 4 (1,2,4), 9 (1,3,9), 25 (1,5,25).
Because only perfect squares of primes have exactly 3 factors.
A number has a GCF of 14 with 42. What could the number be? Give two possible answers.
Any number whose factors include 2 × 7 but no higher shared factors.
Examples: 14, 28, 56, 70, 84…
(Minimum: 14; Maximum: infinite options)
A fraction is very close to 1. If its denominator is 200, give a numerator that makes it closer to 1 than ¾.
Must be greater than 150.
Examples: 160/200, 175/200, 190/200, 199/200…
The LCM of two numbers is 84. One of the numbers is 12.
Give two possible values for the second number.
Numbers whose LCM with 12 = 84 → 7, 14, 21, 28, 42, 84
A zookeeper needs to divide 247 grams of food equally into 12 habitats.
Write the exact mixed number.
Determine whether she should round up, round down, or keep the fraction.
247 ÷ 12 = 20 7/12
Interpretation: Keep the fraction, because food can be measured in partial grams.