When you come across a number like 67 and start questioning its prime status, here are five fast facts to keep in mind that will help you understand why 67 is indeed a prime number:
Fact 1: What is a Prime Number?
A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. This means that for 67 to be a prime number, it must have only two distinct positive divisors: 1 and 67.
Fact 2: Divisibility Tests
To quickly determine if 67 is prime, we can use divisibility rules:
- Divisible by 2: Numbers ending in 2, 4, 6, 8, or 0 are divisible by 2. 67 does not fit this pattern.
- Divisible by 3: Sum the digits (6 + 7 = 13), if the sum is divisible by 3, then the number is too. 13 is not divisible by 3.
- Divisible by 5: Numbers ending in 0 or 5 are divisible by 5. 67 doesn't end in 0 or 5.
- Divisible by other small primes: Checking divisibility by 7 (result 9.57, not an integer), 11 (67 divided by 11 equals 6 remainder 1), and other primes up to the square root of 67 (which is approximately 8.19), we find no integer divisors.
<p class="pro-note">โ Pro Tip: Learning these divisibility rules can save you time when determining if a number is prime or not.</p>
Fact 3: The Sieve of Eratosthenes
One of the oldest methods for finding prime numbers, the Sieve of Eratosthenes, can also verify that 67 is a prime number. You list all numbers up to 67, and then mark off all multiples of 2, 3, 5, 7, 11, etc. After the sieve process, any number not marked off, including 67, remains as a prime number.
- Step 1: List all numbers from 2 to 67.
- Step 2: Cross off multiples of 2, starting with 4, 6, 8, etc.
- Step 3: Cross off multiples of 3, 5, and all primes up to 67.
- Conclusion: 67 remains unmarked, hence prime.
Fact 4: Prime Factorization
67 cannot be expressed as a product of two smaller numbers (other than 1 and itself), which confirms its prime status:
- Prime Factorization: 67 = 1 ร 67
<p class="pro-note">๐ฏ Pro Tip: Always try to break down a number into its smallest factors to verify its primality quickly.</p>
Fact 5: Number Properties
- Odd Number: As 67 is an odd number, it's not divisible by 2.
- Not a Perfect Square: 67 is not a square of any integer, confirming it's not a composite number.
- Unique Divisors: Only 1 and 67 can evenly divide 67.
To Summarize, these facts collectively illustrate that 67 has all the characteristics of a prime number:
- It passes the prime number definition.
- It does not divide evenly by any number other than 1 and itself.
- It survives the Sieve of Eratosthenes.
- Its prime factorization confirms its indivisibility by any smaller numbers.
- Its number properties are consistent with prime numbers.
Explore More with our other tutorials on prime numbers and mathematics, delve deeper into the fascinating world of numbers.
<p class="pro-note">๐ก Pro Tip: Prime numbers are not just curiosities; they are crucial in many fields, from cryptography to solving equations.</p>
<div class="faq-section"> <div class="faq-container"> <div class="faq-item"> <div class="faq-question"> <h3>What makes 67 a prime number?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>67 is a prime number because it has only two distinct positive divisors: 1 and 67 itself.</p> </div> </div> <div class="faq-item"> <div class="faq-question"> <h3>How do you quickly check if a number like 67 is prime?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>Quick methods include using divisibility tests for small primes and the Sieve of Eratosthenes for larger numbers.</p> </div> </div> <div class="faq-item"> <div class="faq-question"> <h3>Can 67 be expressed as a product of two numbers?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>67 can only be expressed as the product of 1 and 67, making it a prime number.</p> </div> </div> <div class="faq-item"> <div class="faq-question"> <h3>What are the common mistakes when checking for prime numbers?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>Common errors include not checking for divisibility by all primes less than the square root of the number, and misunderstanding the definition of a prime number.</p> </div> </div> </div> </div>