131k views
4 votes
Which of the following is true?Enter a, b, c, d, or e.a. 443 is a composite number.b. 541 is a prime number.C. -600 is a composite number.d. 591 is a prime number.ae. 1 is a prime number.

User Torra
by
3.4k points

1 Answer

4 votes

By definition a prime number and a composite number are:

Prime numbers: whole numbers greater than 1, that have only two factors: 1 and the number itself.

Composite numbers: whole numbers greater than 1, that have more than two factors. It is divisible by the number itself, the number 1 and at least one other number.

In that order, 1 is not a prime number and -600 is not a composite number. Options c and e are false.

Now, we need to check 443, 541 and 591.

To check if a number is prime or composite, we have to apply divisibility tests and check if the number is divisible by 2, 5, 3, 11, 7 or 13.

The divisibility rules for these numbers are:

2: If the last digit is an even number.

These numbers are odd, then they are not divisible by 2.

3: a number is completely divisible by 3 if the sum of its digits is divisible by 3.

4+4+3=11 it is not divisible by 3

5+4+1=10 it is not divisible by 3

5+9+1=15 and 1+5=6 it is divisible by 3, then 591 is not a prime number (option d is false).

5: a number is divisible by 5 if the last digit is 0 or 5.

443 and 541 are not divisible by 5.

11: take the alternating sum of the digits in the number, read from left to right. If that is divisible by 11, so is the original number:

443-> 4-4+3=3 it is not divisible by 11

541->5-4+1=2 it is not divisible by 13

13: to check if a number is divisible by 13, we have to add four times of the last digit of the number to the remaining number and repeat the process until you get a two-digit number. Now check if that two-digit number is divisible by 13 or not. If it is divisible, then the given number is divisible by 13.

44+(3*4)=44+12=56 it is not divisible by 13

54+(1*4)=54+4=58 it is not divisible by 13.

Then, 443 and 541 are both prime numbers, then the answer is b. 541 is a prime number.

User Dotwin
by
3.1k points