Math

QuestionIs the number 15 prime, composite, or neither?

Studdy Solution

STEP 1

Assumptions1. The number we are examining is15.

STEP 2

A prime number is a natural number greater than1 that has no positive divisors other than1 and itself. The first few prime numbers are2,,5,7,11, and13.

STEP 3

A composite number is a positive integer that has at least one positive divisor other than one or itself. In other words, a composite number is any positive integer greater than one that is not a prime number.

STEP 4

To determine if15 is prime, composite, or neither, we need to find its divisors. A divisor is a number that divides another number evenly, i.e., without leaving a remainder.

STEP 5

We start by checking if15 can be divided evenly by2.15mod215 \, mod \,2

STEP 6

Calculate the modulus.
15mod2=115 \, mod \,2 =1

STEP 7

Since the result is not zero,2 is not a divisor of15. We move on to the next number,3.
15mod315 \, mod \,3

STEP 8

Calculate the modulus.
15mod3=015 \, mod \,3 =0

STEP 9

Since the result is zero,3 is a divisor of15. This means that15 is not a prime number, as it has more divisors than just and itself.

STEP 10

We continue checking for more divisors to confirm if15 is a composite number. We check the next number,4.
15mod415 \, mod \,4

STEP 11

Calculate the modulus.
15mod4=315 \, mod \,4 =3

STEP 12

Since the result is not zero,4 is not a divisor of15. We move on to the next number,5.
15mod515 \, mod \,5

STEP 13

Calculate the modulus.
15mod5=015 \, mod \,5 =0

STEP 14

Since the result is zero, is a divisor of. This confirms that is a composite number, as it has more than two divisors (,3,, and).
The number is a composite number.

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