8.1

function MultiplicatorUnitFailure() {}

function primitiveMultiply(a, b) {
  if (Math.random() < 0.5)
    return a * b;
  else
    throw new MultiplicatorUnitFailure();
}

function reliableMultiply(a, b) {
  // Your code here.
  for(;;){
	try{
      return primitiveMultiply(a,b)
    }
    catch (e){
      if( !(e instanceof MultiplicatorUnitFailure ))
         throw e;
    }
  }
};

console.log(reliableMultiply(8, 8));
// → 64