What do we call the numbers that cannot be arranged into 2-row arrays?
The numbers that cannot be arranged into 2-row arrays are called prime numbers. Prime numbers are positive integers greater than 1 that have no divisors other than 1 and themselves.
To determine if a number is prime, you can follow these steps:
1. Start with the number you want to check (let's call it n).
2. Iterate from 2 up to the square root of n (since factors of n will not be larger than its square root).
3. For each number i in the iteration, check if n is divisible by i. If it is, then n is not a prime number.
4. If no divisors are found, n is a prime number.
For example, let's check if 13 is a prime number:
1. Let n = 13.
2. Iterate from 2 up to the square root of 13 (which is approximately 3.61).
- Check if 13 is divisible by 2 (it's not).
- Check if 13 is divisible by 3 (it's not).
3. Since there are no divisors, 13 is a prime number.
Therefore, 13 is an example of a number that cannot be arranged into 2-row arrays.