const x0 = new Fixed(123n, 0)   // [123n;0]
const x18 = x0.move(18)         // [123000000000000000000n;18]

const y18 = new Fixed(1n, 18)   // [000000000000000000001n;18]
const z18 = x18.add(y18)        // [123000000000000000001n;18]

const str = z18.toString()      // "123.000000000000000001"
const num = Number(str)         // 123
const int = BigInt(num)         // 123n