diff --git a/commonxl/fmt.go b/commonxl/fmt.go
index daecb1b..9416a72 100644
--- a/commonxl/fmt.go
+++ b/commonxl/fmt.go
@@ -145,6 +145,9 @@ func fracFmtFunc(n int) FmtFunc {
 			return "MUST BE numeric TO FORMAT CORRECTLY"
 		}
 		w, n, d := DecimalToWholeFraction(f, n, n)
+		if n == 0 {
+			return fmt.Sprintf("%d", w)
+		}
 		return fmt.Sprintf("%d %d/%d", w, n, d)
 	}
 }
diff --git a/commonxl/fmt_test.go b/commonxl/fmt_test.go
index c5a9240..d844ff1 100644
--- a/commonxl/fmt_test.go
+++ b/commonxl/fmt_test.go
@@ -6,12 +6,12 @@ import (
 	"time"
 )
 
-type testcase struct {
+type testcaseNums struct {
 	v interface{}
 	s string
 }
 
-var commas = []testcase{
+var commas = []testcaseNums{
 	{10, "10"},
 	{float64(10), "10"},
 	{float64(10) + 0.12345, "10.12345"},
@@ -72,10 +72,11 @@ var commas = []testcase{
 
 func TestCommas(t *testing.T) {
 	cf := addCommas(identFunc)
-
 	for _, c := range commas {
-		if c.s != cf(nil, c.v) {
-			t.Fatalf("commas failed: did not get '%s' for %T(%v)", c.s, c.v, c.v)
+		fs := cf(nil, c.v)
+		if c.s != fs {
+			t.Fatalf("commas failed: get '%s' but expected '%s' for %T(%v)",
+				fs, c.s, c.v, c.v)
 		}
 	}
 }
@@ -103,3 +104,35 @@ func TestDateFormats(t *testing.T) {
 		}
 	}
 }
+func TestBoolFormats(t *testing.T) {
+	ff := makeFormatter(`"yes";"yes";"no"`)
+
+	if "no" != ff(nil, false) {
+		t.Fatal(`false should be "no"`)
+	}
+	if "no" != ff(nil, 0) {
+		t.Fatal(`0 should be "no"`)
+	}
+	if "no" != ff(nil, 0.0) {
+		t.Fatal(`0.0 should be "no"`)
+	}
+
+	/////
+
+	if "yes" != ff(nil, true) {
+		t.Fatal(`true should be "yes"`)
+	}
+	if "yes" != ff(nil, 99) {
+		t.Fatal(`99 should be "yes"`)
+	}
+	if "yes" != ff(nil, -4) {
+		t.Fatal(`-4 should be "yes"`)
+	}
+
+	if "yes" != ff(nil, 4.0) {
+		t.Fatal(`4.0 should be "yes"`)
+	}
+	if "yes" != ff(nil, -99.0) {
+		t.Fatal(`-99.0 should be "yes"`)
+	}
+}
diff --git a/commonxl/frac_test.go b/commonxl/frac_test.go
new file mode 100644
index 0000000..86bd419
--- /dev/null
+++ b/commonxl/frac_test.go
@@ -0,0 +1,63 @@
+package commonxl
+
+import (
+	"math"
+	"testing"
+)
+
+type testcaseFrac struct {
+	v float64
+	s string
+	n int
+}
+
+var fracs = []testcaseFrac{
+	{10, "10", 1},
+	{-10, "-10", 1},
+	{10.5, "10 1/2", 1},
+	{-10.5, "-10 1/2", 1},
+
+	{10.25, "10 1/4", 1},
+	{10.75, "10 3/4", 1},
+	{10.667, "10 2/3", 1},
+
+	{-10.25, "-10 1/4", 1},
+	{-10.75, "-10 3/4", 1},
+	{-10.667, "-10 2/3", 1},
+
+	{3.14159, "3 1/7", 1},
+	{3.14159, "3 1/7", 2},
+	{3.14159, "3 16/113", 3},
+	{3.14159, "3 431/3044", 4},
+	{3.14159, "3 3432/24239", 5},
+	{3.14159, "3 14159/100000", 6},
+
+	{math.Pi, "3 1/7", 1},
+	{math.Pi, "3 1/7", 2},
+	{math.Pi, "3 16/113", 3}, // err = 2.6e-7
+	{math.Pi, "3 16/113", 4}, // better because 431/3044 err = 2.6e-6
+	{math.Pi, "3 14093/99532", 5},
+	{math.Pi, "3 14093/99532", 6},
+
+	{-math.Pi, "-3 1/7", 1},
+	{-math.Pi, "-3 1/7", 2},
+	{-math.Pi, "-3 16/113", 3}, // err = 2.6e-7
+	{-math.Pi, "-3 16/113", 4}, // better because 431/3044 err = 2.6e-6
+	{-math.Pi, "-3 14093/99532", 5},
+	{-math.Pi, "-3 14093/99532", 6},
+
+	// TODO: fixed denominator fractions (e.g. "??/8" )
+	// TODO: string interpolations (e.g. '0 "pounds and " ??/100 "pence"')
+	// examples: https://bettersolutions.com/excel/formatting/number-tab-fractions.htm
+}
+
+func TestFractions(t *testing.T) {
+	for _, c := range fracs {
+		ff := fracFmtFunc(c.n)
+		fs := ff(nil, c.v)
+		if c.s != fs {
+			t.Fatalf("fractions failed: got: '%s' expected: '%s' for %T(%v)",
+				fs, c.s, c.v, c.v)
+		}
+	}
+}
diff --git a/commonxl/numbers.go b/commonxl/numbers.go
index 4ff8856..c3df4c2 100644
--- a/commonxl/numbers.go
+++ b/commonxl/numbers.go
@@ -8,8 +8,15 @@ import (
 // number and fraction approximation with at most nn digits in the numerator
 // and nd digits in the denominator.
 func DecimalToWholeFraction(val float64, nn, nd int) (whole, num, den int) {
-	num, den = DecimalToFraction(val, nn, nd)
-	whole, num = num/den, num%den
+	wholeF, part := math.Modf(val)
+	if part == 0.0 {
+		return int(wholeF), 0, 1
+	}
+	if part < 0.0 {
+		part = -part
+	}
+	whole = int(wholeF)
+	num, den = DecimalToFraction(part, nn, nd)
 	return
 }