Add function

src/index.js

@@ -1,3 +1,124 @@
 module.exports = function toReadable (number) {
-
+    function simpleNumber(simpleNum){
+        switch (simpleNum) {
+            case 1:
+              return 'one';
+            case 2:
+              return 'two';
+            case 3:
+              return 'three';
+            case 4:
+              return 'four';
+            case 5:
+              return 'five';
+            case 6:
+              return 'six';
+            case 7:
+              return 'seven';
+            case 8:
+              return 'eight';  
+            case 9:
+              return 'nine'; 
+            default:
+              return null;
+          }    
+    }
+
+    function complexNumber(number){
+      switch (number) {
+          case 10:
+            return 'ten';
+          case 11:
+            return 'eleven';
+          case 12:
+            return 'twelve';
+          case 13:
+            return 'thirteen';
+          case 14:
+            return 'fourteen';   
+          case 15:
+            return 'fifteen';  
+          case 18:
+            return 'eighteen';
+          case 20:
+            return 'twenty';
+          case 30:
+            return 'thirty';
+          case 40:
+            return 'forty';   
+          case 50:
+            return 'fifty';   
+          case 80:
+            return 'eighty';  
+          default:
+            return null;
+        }    
+    }
+
+    let num = number;
+    let std = '';
+
+    if( num <= 0 ){
+        std = 'zero';
+    }
+
+    const quantity = (num).toString().length;
+    if( quantity === 3 ){
+        const firstNum = Number( (num).toString()[0] );
+        std = (`${simpleNumber(firstNum)} ${'hundred'}`);
+        num = Number( (num).toString().slice(1) );
+        if( num !== 0 ){
+            std = (`${std}${' '}`);
+        }
+    }
+
+    if ( ( num >= 10 && num < 16 ) || num === 18 || num === 20 || num === 30 || num === 80 || num === 50 || num === 40 ){
+        std = (`${std}${complexNumber(num)}`);
+    }
+
+    if( num > 0 && num < 10 ){
+       std = (`${std}${simpleNumber(num)}`);
+    }
+
+    if ( num >= 16 && num < 20 && num !== 18 ){
+      const lastNumber =Number( (num).toString().slice(-1));
+      std = (`${std}${simpleNumber(lastNumber)}${'teen'}`);
+    }
+
+    if ( (num >= 21 && num < 30) ){
+      const lastNumber =Number( (num).toString().slice(-1));
+      std = (`${std}${'twenty'} ${simpleNumber(lastNumber)}`);
+    }
+
+    if ( (num >= 31 && num < 40) ){
+      const lastNumber =Number( (num).toString().slice(-1));
+      std = (`${std}${'thirty'} ${simpleNumber(lastNumber)}`);
+    }
+
+    if ( (num >= 41 && num < 50) ){
+        const lastNumber =Number( (num).toString().slice(-1));
+        std = (`${std}${'forty'} ${simpleNumber(lastNumber)}`);
+      }
+
+    if ( (num >= 51 && num < 60) ){
+        const lastNumber =Number( (num).toString().slice(-1));
+        std = (`${std}${'fifty'} ${simpleNumber(lastNumber)}`);
+      }
+
+    if ( (num >= 81 && num < 90) ){
+      const lastNumber =Number( (num).toString().slice(-1));
+      std = (`${std}${'eighty'} ${simpleNumber(lastNumber)}`);
+    }
+
+    if ( (num >= 60 && num < 80) || (num >= 90 && num < 100) ){
+      const middelNumber =Number( (num).toString()[0] );
+      std = (`${std}${simpleNumber(middelNumber)}${'ty'}`);
+
+      const lastNumber =Number( (num).toString()[1] );
+      if( lastNumber!== 0 ){
+        std = (`${std} ${simpleNumber(lastNumber)}`);
+      }
+    }
+
+    return std;
 }