Create a README.md

README.md

@@ -301,7 +301,8 @@ npm test -- 'playground'
 
 ### References
 
-[▶ Data Structures and Algorithms on YouTube](https://www.youtube.com/playlist?list=PLLXdhg_r2hKA7DPDsunoDZ-Z769jWn4R8)
+- [▶ Data Structures and Algorithms on YouTube](https://www.youtube.com/playlist?list=PLLXdhg_r2hKA7DPDsunoDZ-Z769jWn4R8)
+- [✍🏻 Data Structure Sketches](https://okso.app/showcase/data-structures)
 
 ### Big O Notation
 

src/algorithms/math/factors/README.md

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+# factor
+
+
+What is factor?
+
+Factor is a term in multiplication for a whole number by which a larger whole number can be divided.
+A factor is a number that divides another number, leaving no remainder. 
+a factor is a number that divides another number without leaving any remainder. 
+In contrast, a multiple is a number that, when divided a certain of times by another number, no remainder is left.
+To be the factors of a number, the factor number should exactly divide the number (with 0 remainder).
+There are two methods of finding factors: multiplication and division.
+In addition, rules of divisibility may also be used.
+
+
+## References
+
+https://en.wikipedia.org/wiki/Factor#Mathematics
+
+https://www.storyofmathematics.com/factors-multiples/
+
+https://www.splashlearn.com/math-vocabulary/multiplication/factor

src/algorithms/math/factors/_test_/factors.test.js

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+import { factors } from '../factors';
+
+describe('factors', () => {
+  it('should find factors', () => {
+    expect(factors(1)).toEqual([1]);
+    expect(factors(2)).toEqual([1, 2]);
+    expect(factors(3)).toEqual([1, 3]);
+    expect(factors(4)).toEqual([1, 2, 4]);
+    expect(factors(5)).toEqual([1, 5]);
+    expect(factors(14)).toEqual([1, 2, 7, 14]);
+    expect(factors(40)).toEqual([1, 2, 4, 5, 8, 10, 20, 40]);
+    expect(factors(54)).toEqual([1, 2, 3, 6, 9, 18, 27, 54]);
+    expect(factors(100)).toEqual([1, 2, 4, 5, 10, 20, 25, 50, 100]);
+  });
+});

src/algorithms/math/factors/factors.js

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+/**
+ * Finds the factor of a number.
+ */
+export default function printFactors(x) {
+  console.log('The factors of', x, 'are:');
+  //  looping 
+  for (let i = 1; i <= x; i++) {
+    if (x % i === 0) {
+      console.log(i);
+    }
+  }
+}
+
+//  get the input from the user
+const num = prompt('Enter a positive integer: ');
+printFactors(num);