using System; class NumberStore { int[] numbers = { 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023 }; public ref int FindNumber(int target) { ref int returnVal = ref numbers[0]; var ctr = numbers.Length - 1; while ((ctr > 0) && numbers[ctr] >= target) { returnVal = ref numbers[ctr]; ctr--; } return ref returnVal; } public override string ToString() => string.Join(" ", numbers); }