1 files changed, 39 insertions, 0 deletions
diff --git a/factors/score.go b/factors/score.go
index 707120d..b47aac4 100644
--- a/factors/score.go
+++ b/factors/score.go
@@ -26,3 +26,42 @@ func Score(n uint) float64 {
 	}
 	return float64(factorSum) / float64(n)
 }
+
+// BasicRank returns a rank describing how well a base handles the simplest
+// fractions (1/2, 1/3, 1/4 and 1/5)
+// also known as 2345 Rank
+func BasicRank(n uint) string {
+	var firstRank, secondRank string
+	if n%2 == 0 {
+		if n%3 == 0 {
+			if n%4 == 0 {
+				firstRank = "A"
+			} else {
+				firstRank = "B"
+			}
+		} else {
+			if n%4 == 0 {
+				firstRank = "C"
+			} else {
+				firstRank = "D"
+			}
+		}
+	} else {
+		if n%3 == 0 {
+			firstRank = "E"
+		} else {
+			firstRank = "F"
+		}
+	}
+
+	switch n % 5 {
+	case 0:
+		secondRank = "+"
+	case 1, 4:
+		secondRank = "~"
+	case 2, 3:
+		secondRank = "-"
+	}
+
+	return firstRank + secondRank
+}