3.js

//const cardNumber = 4533787178994213;
//const last4Digits = cardNumber.slice(-4);

// The last4Digits variable should store the last 4 digits of cardNumber
// However, the code isn't working

// Before running the code, make and explain a prediction about why the code won't work
//*Answer
//It won't work because cardNumber is not a string and .slice() only works with strings. It will throw an error.

// Then run the code and see what error it gives.
//*Answer
//Uncaught TypeError: cardNumber.slice is not a function

// Consider: Why does it give this error? Is this what I predicted? If not, what's different?
//*Answer
//I was right. cardNumber is a number not a string and .slice() only works with strings 
// so it needs to be converted to a string to work using .toString()

// Then try updating the expression last4Digits is assigned to, in order to get the correct value
//*Answer
const cardNumber = 4533787178994213;
const last4Digits = cardNumber.toString().slice(-4);
console.log(last4Digits);