title: Convert variable stored in AsyncStorage then state to Number
body: <p>How can I convert an AsyncStorage stored number (stored as a string) to a Number in react native (I am using Expo).</p>
  
  <p>It works converting the string to a number like this:</p>
  
  <pre><code>myNum = Number('3'); // THIS WORKS
  </code></pre>
  
  <p>But this does not work:</p>
  
  <pre><code>myNum = Number(this.state.myStateNum); // This does not work, returns zero
  
  myNum = Math.floor(this.state.myStateNum); // This does not work, returns zero
  </code></pre>
  
  <p>I am getting my variable from AsyncStorage and then storing as a state but I can't figure out why I can't convert it to a number.</p>
  
  <p>If it helps this is how I set using async:</p>
  
  <pre><code>async function setItem(key, value) {
    try {
      await AsyncStorage.setItem(key, value);
      console.log(key, value);
      return value;
    } catch (error) {
    }
  }
  
  setVar = setItem('myStateNum', '3');
  </code></pre>
  
  <p>This is how I get using async:</p>
  
  <pre><code>async componentWillMount() {
    const myStateNumGet = await AsyncStorage.getItem('myStateNum');
    if (myStateNumGet) {
      this.setState({ myStateNum: myStateNumGet });
    } else {
      this.setState({ myStateNum: false });
    }
  }
  </code></pre>
  
  <p>Any suggestions/help would be great.</p>