text: const str1 = '5';
  
  console.log(str1.padStart(2, '0'));
  // expected output: "05"
  
  const fullNumber = '2034399002125581';
  const last4Digits = fullNumber.slice(-4);
  const maskedNumber = last4Digits.padStart(fullNumber.length, '*');
  
  console.log(maskedNumber);
  // expected output: "************5581"