diff --git a/numbers.go b/numbers.go
new file mode 100644
index 0000000..4fc16f8
--- /dev/null
+++ b/numbers.go
@@ -0,0 +1,235 @@
+package numbers
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+)
+
+func Scale(num float64, digits int) float64 {
+	if num == 0.0 {
+		return 0.0
+	}
+	if math.IsNaN(num) {
+		return 0.0
+	}
+	if math.IsInf(num, 0) {
+		return num
+	}
+
+	original := num
+	num = math.Abs(num)
+
+	d := math.Ceil(math.Log10(num))
+	power := digits - int(d)
+	magnitude := math.Pow10(power)
+	shifted := math.Ceil(num * magnitude)
+	result := shifted / magnitude
+
+	result = math.Copysign(result, original)
+	return result
+}
+
+func SlideScale(num float64) float64 {
+	if math.Abs(num) < 100.0 {
+		return Scale(num, 1)
+	}
+	return Scale(num, 2)
+}
+
+func ScaleDown(num float64, digits int) float64 {
+	if num == 0.0 {
+		return 0.0
+	}
+	if math.IsNaN(num) {
+		return 0.0
+	}
+	if math.IsInf(num, 0) {
+		return num
+	}
+
+	original := num
+	num = math.Abs(num)
+
+	result := 0.0
+
+	if num < 1.0 {
+		result = math.Floor(num*10.0) / 10.0
+	} else {
+		d := math.Ceil(math.Log10(num))
+		power := digits - int(d)
+		magnitude := math.Pow10(power)
+		shifted := math.Floor(num * magnitude)
+		result = shifted / magnitude
+	}
+
+	result = math.Copysign(result, original)
+	return result
+}
+
+func SlideScaleDown(num float64) float64 {
+	if math.Abs(num) < 100.0 {
+		return ScaleDown(num, 1)
+	}
+	return ScaleDown(num, 2)
+}
+
+func CentsToDollars(cents float64) string {
+	dollars := cents / 100.0
+	return fmt.Sprintf("$%.2f", dollars)
+}
+
+func AddDelimiters(num float64) string {
+	s := strconv.FormatFloat(num, 'f', 3, 64)
+	if num < 1000.0 {
+		return s
+	}
+	pieces := strings.Split(s, ".")
+	digits := []string(nil)
+
+	inum := pieces[0]
+	x := len(inum)
+	for x > 2 {
+		digits = append(digits, inum[x-3:x])
+		x -= 3
+	}
+	if x > 0 {
+		digits = append(digits, inum[0:x])
+	}
+
+	for i, j := 0, len(digits)-1; i < j; i, j = i+1, j-1 {
+		digits[i], digits[j] = digits[j], digits[i]
+	}
+
+	// drop the fraction
+	// result := strings.Join(digits, ",") + "." + pieces[1]
+	result := strings.Join(digits, ",")
+
+	return result
+}
+
+func AddDelimitersInt(num int) string {
+	inum := strconv.Itoa(num)
+	digits := []string(nil)
+
+	x := len(inum)
+	for x > 2 {
+		digits = append(digits, inum[x-3:x])
+		x -= 3
+	}
+	if x > 0 {
+		digits = append(digits, inum[0:x])
+	}
+
+	for i, j := 0, len(digits)-1; i < j; i, j = i+1, j-1 {
+		digits[i], digits[j] = digits[j], digits[i]
+	}
+
+	// drop the fraction
+	// result := strings.Join(digits, ",") + "." + pieces[1]
+	result := strings.Join(digits, ",")
+
+	return result
+}
+
+func Display(num float64) string {
+	if num >= 10000.0 {
+		return Humanize(num)
+	}
+	if num >= 1000.0 {
+		return AddDelimiters(num)
+	}
+
+	if num > 1.0 && math.Floor(num) == num {
+		return fmt.Sprintf("%.0f", num)
+	}
+
+	if num == 0.0 {
+		return "0"
+	}
+
+	return fmt.Sprintf("%.3f", num)
+}
+
+func Humanize(num float64) string {
+	var exponent = 0.0
+	if num != 0 {
+		exponent = math.Floor(math.Log10(math.Abs(num)))
+	}
+
+	if exponent >= 3 {
+		unit := "K"
+		dispExponent := 3
+		if exponent >= 15 {
+			unit = "Q"
+			dispExponent = 15
+		} else if exponent >= 12 {
+			unit = "T"
+			dispExponent = 12
+		} else if exponent >= 9 {
+			unit = "G"
+			dispExponent = 9
+		} else if exponent >= 6 {
+			unit = "M"
+			dispExponent = 6
+		}
+		num /= math.Pow10(dispExponent)
+		return fmt.Sprintf("%.2f%s", num, unit)
+	}
+
+	return AddDelimiters(num)
+}
+
+func Words(num float64) string {
+	var exponent = 0.0
+	if num != 0 {
+		exponent = math.Floor(math.Log10(math.Abs(num)))
+	}
+
+	if exponent >= 3 {
+		unit := "thousand"
+		dispExponent := 3
+		if exponent >= 15 {
+			unit = "quadrillion"
+			dispExponent = 15
+		} else if exponent >= 12 {
+			unit = "trillion"
+			dispExponent = 12
+		} else if exponent >= 9 {
+			unit = "billion"
+			dispExponent = 9
+		} else if exponent >= 6 {
+			unit = "million"
+			dispExponent = 6
+		}
+		num /= math.Pow10(dispExponent)
+		return fmt.Sprintf("%.2f %s", num, unit)
+	}
+
+	return AddDelimiters(num)
+}
+
+func Percentage(current, old float64) float64 {
+	if old == 0.0 {
+		return 0.0
+	}
+	return 100.0 * (current - old) / old
+}
+
+func DisplayPercentage(percentage float64) string {
+	return Display(percentage)
+}
+
+// using midpoint method
+func PercentageMid(current, old float64) float64 {
+	mid := 0.5 * (current + old)
+	if mid == 0.0 {
+		return 0.0
+	}
+	return 100.0 * (current - old) / mid
+}
+
+func Megabytes(bytes uint64) float64 {
+	return float64(bytes) / (1024.0 * 1024.0)
+}
diff --git a/numbers_test.go b/numbers_test.go
new file mode 100644
index 0000000..5813b1d
--- /dev/null
+++ b/numbers_test.go
@@ -0,0 +1,120 @@
+package numbers
+
+import (
+	"testing"
+)
+
+func TestAddDelim(t *testing.T) {
+	s := AddDelimiters(32.3)
+	if s != "32.300" {
+		t.Errorf("expected 32.3, not '%s'", s)
+	}
+
+	s = AddDelimiters(3032.3)
+	if s != "3,032" {
+		t.Errorf("expected 3,032.3000, not '%s'", s)
+	}
+
+	s = AddDelimiters(123131231233032.3)
+	if s != "123,131,231,233,032" {
+		t.Errorf("expected 3,032.3000, not '%s'", s)
+	}
+
+	s = AddDelimiters(1123131231233032.3)
+	if s != "1,123,131,231,233,032" {
+		t.Errorf("expected 3,032.300, not '%s'", s)
+	}
+	s = AddDelimiters(12123131231233032.3)
+	if s != "12,123,131,231,233,032" {
+		t.Errorf("expected 3,032.300, not '%s'", s)
+	}
+
+	s = AddDelimitersInt(12123131231233032)
+	if s != "12,123,131,231,233,032" {
+		t.Errorf("expected 3,032.300, not '%s'", s)
+	}
+}
+
+type dtest struct {
+	num    float64
+	result string
+}
+
+var dispTests = []dtest{{999.0, "999"},
+	{0.3145, "0.315"},
+	{1300000, "1.30M"},
+	{871300000, "871.30M"},
+	{1300000000, "1.30G"},
+	{13000000000, "13.00G"},
+	{1300000000000, "1.30T"},
+	{1300000000000000, "1.30Q"},
+	{0.0, "0"},
+	{0.0000, "0"},
+	{1001.0, "1,001"}}
+
+func TestDisplay(t *testing.T) {
+	for i, v := range dispTests {
+		s := Display(v.num)
+		if s != v.result {
+			t.Errorf("%d: expected '%s', got '%s'", i, v.result, s)
+		}
+	}
+}
+
+func TestPercentage(t *testing.T) {
+	if Percentage(100.0, 0.0) != 0.0 {
+		t.Errorf("expected 0, got %f", Percentage(100.0, 0.0))
+	}
+	if PercentageMid(100.0, 0.0) != 200.0 {
+		t.Errorf("expected 200%%, got %f", PercentageMid(100.0, 0.0))
+	}
+	if Percentage(110.0, 100.0) != 10.0 {
+		t.Errorf("expected 10%%, got %f", Percentage(110.0, 100.0))
+	}
+	if PercentageMid(110.0, 100.0) != 9.523809523809524 {
+		t.Errorf("expected 10%%, got %f", PercentageMid(110.0, 100.0))
+	}
+}
+
+func TestScale(t *testing.T) {
+	if Scale(1.23, 1) != 2.0 {
+		t.Errorf("expected 2.0, got %f", Scale(1.23, 1))
+	}
+
+	if ScaleDown(1.23, 1) != 1.0 {
+		t.Errorf("down scale to 1.0, got %f", ScaleDown(1.23, 1))
+	}
+	if ScaleDown(2.9, 1) != 2.0 {
+		t.Errorf("down scale to 2.0, got %f", ScaleDown(2.9, 1))
+	}
+	if ScaleDown(2934.0, 1) != 2000.0 {
+		t.Errorf("down scale to 2000.0, got %f", ScaleDown(2934.0, 1))
+	}
+	if Scale(2934.0, 1) != 3000.0 {
+		t.Errorf("up scale to 3000.0, got %f", Scale(2934.0, 1))
+	}
+	if Scale(-2.3, 1) != -3.0 {
+		t.Errorf("expected -3.0, got %f", Scale(-2.3, 1))
+	}
+	if Scale(0.25, 1) != 0.3 {
+		t.Errorf("expected 0.3, got %f", Scale(0.25, 1))
+	}
+	if Scale(0.00003, 1) != 0.00003 {
+		t.Errorf("expected 0.00003, got %f", Scale(0.00003, 1))
+	}
+	if Scale(0.000023, 1) != 0.00003 {
+		t.Errorf("expected 0.00003, got %f", Scale(0.000023, 1))
+	}
+	if Scale(-0.000023, 1) != -0.00003 {
+		t.Errorf("expected -0.00003, got %f", Scale(-0.000023, 1))
+	}
+	if Scale(6210.0, 2) != 6300.0 {
+		t.Errorf("Scale(6210, 2) == %v, expected 6300.0", Scale(6210.0, 2))
+	}
+	if ScaleDown(6210.0, 2) != 6200.0 {
+		t.Errorf("ScaleDown(6210, 2) == %v, expected 6200.0", ScaleDown(6210.0, 2))
+	}
+	if Scale(0.251, 2) != 0.26 {
+		t.Errorf("scale 0.251, 2 = %v, expected 0.26", Scale(0.251, 2))
+	}
+}