math: add Remainder example

Change-Id: I4b0fa69a36b04103473aa08e246fa193315ac5aa
Reviewed-on: https://go-review.googlesource.com/c/go/+/353689
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/src/math/example_test.go b/src/math/example_test.go
index 9fc1967..a26d8cb 100644
--- a/src/math/example_test.go
+++ b/src/math/example_test.go
@@ -162,6 +162,11 @@
 	// Output: 2.0
 }
 
+func ExampleRemainder() {
+	fmt.Printf("%.1f", math.Remainder(100, 30))
+	// Output: 10.0
+}
+
 func ExampleMod() {
 	c := math.Mod(7, 4)
 	fmt.Printf("%.1f", c)