diff --git a/src/pkg/math/const.go b/src/pkg/math/const.go
index a108d3e294d..282561f98bb 100644
--- a/src/pkg/math/const.go
+++ b/src/pkg/math/const.go
@@ -49,5 +49,3 @@ const (
 	MaxUint32 = 1<<32 - 1
 	MaxUint64 = 1<<64 - 1
 )
-
-// BUG(rsc): The manual should define the special cases for all of these functions.
diff --git a/src/pkg/math/pow10.go b/src/pkg/math/pow10.go
index 20f91bcb70c..f5ad28bb4b0 100644
--- a/src/pkg/math/pow10.go
+++ b/src/pkg/math/pow10.go
@@ -9,6 +9,10 @@ package math
 var pow10tab [70]float64
 
 // Pow10 returns 10**e, the base-10 exponential of e.
+//
+// Special cases are:
+//	Pow10(e) = +Inf for e > 309
+//	Pow10(e) = 0 for e < -324
 func Pow10(e int) float64 {
 	if e <= -325 {
 		return 0