If the number of bits in the hour is equal to the requested number of LEDs, then its a valid hour:

```
var readBinaryWatch = function(num) {
var hour,
minutes,
numBits,
result = [],
hourFormat = "";
for(hour = 0; hour <= 11; hour++){
for(minutes = 0; minutes <= 59; minutes++){
// Count the number of 'one' bits in each number
numBits = hour.toString(2).split(1).length - 1;
numBits += minutes.toString(2).split(1).length - 1;
// If the number of bits in the hour is the same as the requested number add it to the results
if(numBits === num){
// Format the output, if the minutes are less than 10 add a zero at the beggining of the string
hourFormat = hour.toString() + ":" + (minutes < 10? '0' + minutes.toString() : minutes.toString());
result.push(hourFormat);
}
}
}
return result;
};
```