diff --git a/isnumeric.go b/isnumeric.go
new file mode 100644
index 0000000..e865fe8
--- /dev/null
+++ b/isnumeric.go
@@ -0,0 +1,29 @@
+package jsonint
+
+func isNumeric(data []byte) bool {
+	if len(data) <= 0 {
+		return false
+	}
+
+	{
+		datum := data[0]
+
+		if '-' == datum || '+' == datum {
+			data = data[1:]
+
+			if len(data) <= 0 {
+				return false
+			}
+		}
+	}
+
+	// This is safe to do even though it is UTF-8 encoded Unicode.
+	for _, datum := range data {
+
+		if datum < '0' || '9' < datum {
+			return false
+		}
+	}
+
+	return true
+}
diff --git a/isnumeric_test.go b/isnumeric_test.go
new file mode 100644
index 0000000..9c7d6e6
--- /dev/null
+++ b/isnumeric_test.go
@@ -0,0 +1,288 @@
+package jsonint
+
+import (
+	"testing"
+)
+
+func TestIsNumeric(t *testing.T) {
+
+	tests := []struct{
+		Value []byte
+		Expected bool
+	}{
+		{
+			Value: nil,
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte(""),
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte(" "),
+			Expected: false,
+		},
+		{
+			Value: []byte("  "),
+			Expected: false,
+		},
+		{
+			Value: []byte("   "),
+			Expected: false,
+		},
+		{
+			Value: []byte("    "),
+			Expected: false,
+		},
+		{
+			Value: []byte("     "),
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte("apple"),
+			Expected: false,
+		},
+		{
+			Value: []byte("banana"),
+			Expected: false,
+		},
+		{
+			Value: []byte("cherry"),
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte("ONCE"),
+			Expected: false,
+		},
+		{
+			Value: []byte("TWICE"),
+			Expected: false,
+		},
+		{
+			Value: []byte("THRICE"),
+			Expected: false,
+		},
+		{
+			Value: []byte("FOURCE"),
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte("one"),
+			Expected: false,
+		},
+		{
+			Value: []byte("two"),
+			Expected: false,
+		},
+		{
+			Value: []byte("three"),
+			Expected: false,
+		},
+		{
+			Value: []byte("four"),
+			Expected: false,
+		},
+		{
+			Value: []byte("five"),
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte(`"-255"`),
+			Expected: false,
+		},
+
+		{
+			Value: []byte(`"-5"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"-4"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"-3"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"-2"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"-1"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"0"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"1"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"2"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"3"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"4"`),
+			Expected: false,
+		},
+		{
+			Value: []byte(`"5"`),
+			Expected: false,
+		},
+
+		{
+			Value: []byte(`"255"`),
+			Expected: false,
+		},
+
+
+
+		{
+			Value: []byte("-255"),
+			Expected: true,
+		},
+
+		{
+			Value: []byte("-5"),
+			Expected: true,
+		},
+		{
+			Value: []byte("-4"),
+			Expected: true,
+		},
+		{
+			Value: []byte("-3"),
+			Expected: true,
+		},
+		{
+			Value: []byte("-2"),
+			Expected: true,
+		},
+		{
+			Value: []byte("-1"),
+			Expected: true,
+		},
+		{
+			Value: []byte("0"),
+			Expected: true,
+		},
+		{
+			Value: []byte("1"),
+			Expected: true,
+		},
+		{
+			Value: []byte("2"),
+			Expected: true,
+		},
+		{
+			Value: []byte("3"),
+			Expected: true,
+		},
+		{
+			Value: []byte("4"),
+			Expected: true,
+		},
+		{
+			Value: []byte("5"),
+			Expected: true,
+		},
+
+		{
+			Value: []byte("255"),
+			Expected: true,
+		},
+
+
+
+		{
+			Value: []byte("-0"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+0"),
+			Expected: true,
+		},
+
+
+
+		{
+			Value: []byte("+0"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+1"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+2"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+3"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+4"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+5"),
+			Expected: true,
+		},
+		{
+			Value: []byte("+255"),
+			Expected: true,
+		},
+
+
+
+		{
+			Value: []byte("-"),
+			Expected: false,
+		},
+		{
+			Value: []byte("+"),
+			Expected: false,
+		},
+	}
+
+	for testNumber, test := range tests {
+
+		actual := isNumeric(test.Value)
+		expected := test.Expected
+
+		if expected != actual {
+			t.Errorf("For test #%d, the actual value return from isNumeric() is not what was expected.", testNumber)
+			t.Logf("EXPECTED: %t", expected)
+			t.Logf("ACTUAL:   %t", actual)
+			t.Logf("VALUE: %#v", test.Value)
+			t.Logf("VALUE: %q", test.Value)
+			continue
+		}
+
+	}
+}