diff --git a/numbers.go b/numbers.go
index d4e407e..ab8c01d 100644
--- a/numbers.go
+++ b/numbers.go
@@ -42,6 +42,33 @@ var Nine = New(9, 0)
 // Ten defines value 10 in decimal format
 var Ten = New(10, 0)
 
+// Eleven defines value 11 in decimal format
+var Eleven = New(11, 0)
+
+// Twelve defines value 12 in decimal format
+var Twelve = New(12, 0)
+
+// Thirteen defines value 13 in decimal format
+var Thirteen = New(13, 0)
+
+// Fourteen defines value 14 in decimal format
+var Fourteen = New(14, 0)
+
+// Fifteen defines value 15 in decimal format
+var Fifteen = New(15, 0)
+
+// Sixteen defines value 16 in decimal format
+var Sixteen = New(16, 0)
+
+// Seventeen defines value 17 in decimal format
+var Seventeen = New(17, 0)
+
+// Eighteen defines value 18 in decimal format
+var Eighteen = New(18, 0)
+
+// Nineteen defines value 19 in decimal format
+var Nineteen = New(19, 0)
+
 // Twenty defines value 20 in decimal format
 var Twenty = New(20, 0)
 
diff --git a/sqrt.go b/sqrt.go
index 804586c..b0fb841 100644
--- a/sqrt.go
+++ b/sqrt.go
@@ -12,6 +12,9 @@ func (d Decimal) Sqrt() Decimal {
 // SqrtRound returns the square root of d, the result will have
 // precision digits after the decimal point. The bool precise returns whether the precision was reached
 func (d Decimal) SqrtRound(precision int32) (Decimal, bool) {
+	if d.LessThanOrEqualZero() {
+		return Zero, false
+	}
 	cutoff := New(1, -precision)
 	lo := Zero
 	hi := d
diff --git a/sqrt_test.go b/sqrt_test.go
new file mode 100644
index 0000000..7c1525e
--- /dev/null
+++ b/sqrt_test.go
@@ -0,0 +1,24 @@
+package decimal
+
+import (
+	"testing"
+)
+
+func TestSqrt(t *testing.T) {
+	tables := []struct {
+		x Decimal
+		n Decimal
+	}{
+		{One, One},
+		{Four, Two},
+		{Sixteen, Four},
+		{Two, NewFromFloat(1.4142135623730951)},
+	}
+
+	for _, table := range tables {
+		result := table.x.Sqrt()
+		if result.NotEqual(table.n) {
+			t.Errorf("Sqrt of (%v) was incorrect, got: %v, want: %v.", table.x.String(), result.String(), table.n.String())
+		}
+	}
+}