//decimal number system
let decimal = 42;

//octal number system
let octal = 0o42;
//octal is 34

//hexadecimal number system
let hexadecimal = 0x42;
//hexadecimal is 66

//binary number system
let binary = 0b1010;
//binary is 10

//42 to decimal string
let sDecimal = decimal.toString();
//sDecimal is "42"

//42 to octal string
let sOctal = decimal.toString(8);
//sOctal is "52"

//42 to hexadecimal string
let sHexadecimal = decimal.toString(16);
//sHexadecimal is "2a"

//42 to binary string
let sBinary = decimal.toString(2);
//sBinary is "101010"

console.log("octal =", octal);
console.log("hexadecimal =", hexadecimal);
console.log("binary =", binary);
console.log("sDecimal =", sDecimal);
console.log("sOctal =", sOctal);
console.log("sHexadecimal =", sHexadecimal);
console.log("sBinary =", sBinary);