SCAT Mathematical Reasoning: Number Properties 3

Question 1

Which of the following is a prime number?

Accepted Answer

41

Answer

41 has no factors other than 1 and itself; 27=3³, 33=3×11, and 51=3×17 are all composite.

Question 2

What is the prime factorization of 36?

Accepted Answer

2² × 3²

Answer

36 = 2 × 2 × 3 × 3 = 2² × 3², which uses only prime bases.

Question 3

How many prime numbers are there between 10 and 20?

Accepted Answer

4

Answer

The primes between 10 and 20 are 11, 13, 17, and 19 — a total of 4 primes.

Question 4

Which of the following is a composite number?

Accepted Answer

25

Answer

25 = 5 × 5, so it has factors other than 1 and itself, making it composite.

Question 5

What is the smallest prime number greater than 20?

Accepted Answer

23

Answer

23 is prime because it has no factors other than 1 and 23; 21=3×7, 22=2×11, and 24 are composite.

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