Write a bash script to calculate the frequency of each word in a text file words.txt.
For simplicity sake, you may assume:
words.txt contains only lowercase characters and space ' ' characters. Each word must consist of lowercase characters only. Words are separated by one or more whitespace characters. Example:
Assume that words.txt has the following content:
the day is sunny the the the sunny is is Your script should output the following, sorted by descending frequency:

Given a text file file.txt that contains a list of phone numbers (one per line), write a one-liner bash script to print all valid phone numbers.
You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)
You may also assume each line in the text file must not contain leading or trailing white spaces.
Example:

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the 10 001st prime number?
At first glance, a simple iteration whilst checking if index position is prime, would suffice.
A pseudocode attempt:
sum = 0 for i = 2; i <= ?; i++ { if(isPrime(i)){ sum++ if ( sum >= 10001) { return i } } } Using the solution in go to check if is prime from former examples:

The sum of the squares of the first ten natural numbers is,
$$ 1^x1D2 + 2^2 + … + 10^2 = 385 $$
The square of the sum of the first ten natural numbers is,
$$ (1 + 2 + … + 10)^2 = 552 = 3025 $$
Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.

2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?
At first glance, and as a concept refresher, we’ll have to use **GCD* and **LCM**.
GCD stands for Greatest Common Divisor. GCD is the largest number that divides the given numbers.

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
Find the largest palindrome made from the product of two 3-digit numbers
The first observation is that the number should be in the range of 10000 and 998001. There’s a couple aproaches to the problem, such as:
Multiplicating two 3-digit numbers and checking the result if its a palindrome Creating palindromes and getting the factors to see if that pair is what we’re looking for.

The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?
We neeed to find the largest prime factor of 600851475143.
We know that the largest prime factor of a number, its the number itself.
As a concept refresher, any prime number is only divisible by 1 ant itself, thus, when dividing by a certain number, there should not be a reminder.

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, …
By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
package main import ( "fmt" "time" ) func main() { start := time.

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
package main import "fmt" func main() { sum := 0 for i := 0; i < 1000; i++ { if i % 3 == 0 || i % 5 == 0 { sum += i } } fmt.