eQuizShow

Prime Time Unit Review

LCM or GCF

Question: Would you use the GCF or the LCM to solve the following problem?
Gina has 15 apples and 20 candy bars.  How many people could share these equally?

Answer: Greatest Common Factor or GCF

Question: Would you use the GCF or the LCM to solve the following problem?
A small neon sign blinks every 5 seconds and a larger neon sign blinks every 9 seconds.  The blink at exactly the same time,when will they both blink at exactly the same time again?

Answer: Least Common Multiple or LCM

Question: If you are finding the LCM of two numbers, will it be a larger or smaller number than the two given numbers?
Answer: larger

Question: How many factors does the number 100 have?
Answer: 10 factors

Question: If you calculate the GCF and the LCM of 18 and 24, which will be larger (GCF or LCM)?
Answer: Least Common Multiple

Find LCM

Question: What is the LCM for 14 and 16?
Answer: 112

Question: Find the LCM of 20 and 30.  
Answer: LCM = 60

Question: A small sign blinks every 12 seconds and the larger sign blinks every 9 minutes.  When will they blink at exactly the same time?
Answer: 36

Question: Find the LCM of 13 and 21.  
Answer: LCM = 273

Question: If the factor string for two numbers is 2 x 3 x 5 and 2 x 2 x 7, what is the LCM?
Answer: LCM = 420

Find GCF

Question: Find the GCF of 21 and 35.
Answer: The GCF is 7

Question: Find the GCF of 36 and 48.
Answer: GCF = 12

Question: What is the greatest common factor of 38 and 39?
Answer: 1

Question: If the prime factorization for two numbers is 3 x 5 x 7 and 2 x 3 x 7, what is the GCF of these numbers?
Answer: 21 because 3 x 7

Question: If the GCF of two numbers is 100, are the numbers greater than or less than 100?
Answer: greater (The factors are always smaller.  Example: 200 and 300 have the gcf of 100)

Prime Factorization

Question: What number has the prime factorization of 3 x 5 x 11?
Answer: 165

Question: Write the following prime factorization in exponent form.
3 x 2 x 5 x 7 x 3 x 5

Answer: 2 x 3 to the second power x 5 to the second power x 7
(sorry couldn't use exponents in this program!!)


Question: What is the prime factorization for 160 in expanded form?
Answer: 2 x 2 x 2 x 2 x 2 x 5

Question: What is the prime factorization of 255?
Answer: 5 x 3 x 17

Question: What is the prime factorization for 171?
Answer: 3 x 57

Word Problems

Question: If Jane and her sister start running at the same time from the same location and Jane runs a lap in 12 minutes and her sister runs a lap in 15 minutes, how long until they will finish a lap at exactly the same time?
Answer: 60 minutes

Question: Find the multiples of 21 that are less than 100.
Answer: 21, 42, 63, 84

Question: Mrs. Diaz has 100 pencils to share with students and 75 erasers.  What is the most students she could share the supplies with were each student gets an equal amount of pencils and erasers without any extras?
Answer: 25 students would each get 4 pencils and 3 erasers

Question: Catherine's mom only lets her have candy every Saturday but lets her have pop every 3 days.  If she had them both today, when will she get to have them on exactly the same day?
Answer: In 21 days.

Question: Mystery Number:  
Clue #1:  My number is a multiple of 2 and 7.
Clue #2:  My number is less than 100 but greater than 50.
Clue #3:  My number is the product of three different prime numbers.

Answer: 70