diff --git a/koboldsim/util.go b/koboldsim/util.go
new file mode 100644
index 0000000..b6cbd42
--- /dev/null
+++ b/koboldsim/util.go
@@ -0,0 +1,22 @@
+package koboldsim
+
+import "math"
+
+// Generic helper functions not directly attached to Card Sim Engine mechanics.
+
+// Mean calculates the mathematical mean of its arguments (the sum, divided
+// by the number of elements). If it is called with no arguments, it returns
+// NaN ("not a number"). If there are contradictory infinities among the
+// arguments, it also returns NaN. Overflowing or underflowing can create an
+// infinity.
+func Mean(vals ...float64) float64 {
+	if len(vals) == 0 {
+		return math.NaN()
+	}
+
+	total := 0.0
+	for _, x := range vals {
+		total += x
+	}
+	return total / float64(len(vals))
+}