diff --git a/src/formatters/formatLatin.test.ts b/src/formatters/formatLatin.test.ts
new file mode 100644
index 0000000..1b9b571
--- /dev/null
+++ b/src/formatters/formatLatin.test.ts
@@ -0,0 +1,12 @@
+import { describe, expect, test } from "@jest/globals";
+import { formatLatin } from "./formatLatin";
+
+const accentString =
+  "áéíóúüñ¿¡àâèêëîïôûàãàãçàèéìòóùäöüßáéíóúáéíóúąćęłńóśźżáčďéěíňóřšťúůýžćčđšžáéíóúüαβγδεζηθικλμνξοπρστυφχψωçğıİöşüابتثجحخدذرزسشصضطظعغ";
+const latinString = "aeiou";
+
+describe("formatLatin", () => {
+  test("should return a-z", () => {
+    expect(formatLatin(accentString)).toBe(latinString);
+  });
+});
diff --git a/src/formatters/formatLatin.ts b/src/formatters/formatLatin.ts
new file mode 100644
index 0000000..c346ab7
--- /dev/null
+++ b/src/formatters/formatLatin.ts
@@ -0,0 +1,4 @@
+export const formatLatin = (text: string): string => {
+  let normalized = text.normalize("NFKD");
+  return normalized;
+};
diff --git a/src/math/normaliseArray.ts b/src/math/normaliseArray.ts
new file mode 100644
index 0000000..24c56f4
--- /dev/null
+++ b/src/math/normaliseArray.ts
@@ -0,0 +1,10 @@
+import { max } from "./max";
+import { min } from "./min";
+import { normaliseNumber } from "./normaliseNumber";
+
+export const normaliseArray = (values: number[]) => {
+  const minValue = min(values);
+  const maxValue = max(values);
+
+  return values.map((value) => normaliseNumber(value, minValue, maxValue));
+};
diff --git a/src/math/normaliseNumber.ts b/src/math/normaliseNumber.ts
new file mode 100644
index 0000000..96a34c7
--- /dev/null
+++ b/src/math/normaliseNumber.ts
@@ -0,0 +1,5 @@
+export const normaliseNumber = (
+  value: number,
+  minValue: number,
+  maxValue: number
+) => (value - minValue) / (maxValue - minValue);
diff --git a/src/math/percentageChange.test.ts b/src/math/percentageChange.test.ts
index 8771ef5..7b96222 100644
--- a/src/math/percentageChange.test.ts
+++ b/src/math/percentageChange.test.ts
@@ -8,7 +8,13 @@ describe("percentageChange", () => {
         current: 10,
         previous: 12,
       })
-    ).toBe(-16.67);
+    ).toBe(-0.1667);
+    expect(
+      percentageChange({
+        current: 12,
+        previous: 10,
+      })
+    ).toBe(0.2);
     expect(
       percentageChange({
         current: 0,
diff --git a/src/math/percentageChange.ts b/src/math/percentageChange.ts
index 3b5dfd5..1d95a4c 100644
--- a/src/math/percentageChange.ts
+++ b/src/math/percentageChange.ts
@@ -9,8 +9,8 @@ export const percentageChange = ({
 }): number => {
   if (!isPositiveInt(previous) || !isPositiveInt(current)) return 0;
   if (current === 0 && previous === 0) return 0;
-  if (current === 0 && previous !== 0) return -100;
-  if (current !== 0 && previous === 0) return 100;
-  const perChange = ((current - previous) * 100) / previous;
-  return parseFloat(perChange.toFixed(2));
+  if (current === 0 && previous !== 0) return -1;
+  if (current !== 0 && previous === 0) return 1;
+  const perChange = (current - previous) / previous;
+  return parseFloat(perChange.toFixed(4)); // 4 decimal places so when formatting to % two decimal places are shown
 };
diff --git a/src/random/randomInt.test.ts b/src/random/randomInt.test.ts
index b8e45d2..b9c5efc 100644
--- a/src/random/randomInt.test.ts
+++ b/src/random/randomInt.test.ts
@@ -8,8 +8,8 @@ describe("randomInt", () => {
   });
 
   test("args", async () => {
-    expect(randomInt(12, 20)).toBeGreaterThanOrEqual(12);
-    expect(randomInt(12, 12)).toBeLessThanOrEqual(12);
-    expect(randomInt(11, 12)).toBeLessThanOrEqual(13);
+    expect(randomInt({ min: 12, max: 20 })).toBeGreaterThanOrEqual(12);
+    expect(randomInt({ min: 12, max: 12 })).toBeLessThanOrEqual(12);
+    expect(randomInt({ min: 11, max: 12 })).toBeLessThanOrEqual(13);
   });
 });
diff --git a/src/random/randomInt.ts b/src/random/randomInt.ts
index f3717c2..706b958 100644
--- a/src/random/randomInt.ts
+++ b/src/random/randomInt.ts
@@ -1,35 +1,43 @@
-export const randomInt = (min: number = -100, max: number = 100): number => {
+export const randomInt = ({
+  min = -100,
+  max = 100,
+}: {
+  min?: number;
+  max?: number;
+} = {}): number => {
   min = Math.ceil(min); // in case is a float
   max = Math.floor(max); // in case is a float
   return Math.floor(Math.random() * (max - min + 1) + min);
 };
 
-export const randomPositiveInt = (max: number = 100): number =>
-  randomInt(1, max);
-
-export const randomNegativeInt = (min: number = -100): number =>
-  randomInt(min, -1);
-
-export const randomMaxSafeInt = () =>
-  randomInt(-Number.MAX_SAFE_INTEGER, Number.MAX_SAFE_INTEGER);
-
-export const randomMaxInt = () =>
-  randomInt(-Number.MAX_VALUE, Number.MAX_VALUE);
-
-export const randomPercentage = ({
-  min,
-  max,
+export const randomPositiveInt = ({
+  min = 1,
+  max = 100,
 }: {
   min?: number;
   max?: number;
-} = {}) => randomInt(min ?? -100, max ?? 100);
+} = {}): number =>
+  randomInt({
+    min,
+    max,
+  });
 
-export const randomPositivePercentage = ({
-  min,
-  max,
+export const randomNegativeInt = ({
+  min = -100,
+  max = -1,
 }: {
   min?: number;
   max?: number;
-} = {}) => randomInt(min ?? 1, max ?? 100);
+} = {}): number =>
+  randomInt({
+    min,
+    max,
+  });
+
+export const randomMaxSafeInt = () =>
+  randomInt({ min: -Number.MAX_SAFE_INTEGER, max: Number.MAX_SAFE_INTEGER });
+
+export const randomMaxInt = () =>
+  randomInt({ min: -Number.MAX_VALUE, max: Number.MAX_VALUE });
 
-export const randomFormattedPercentage = () => randomPercentage() + "%";
+export const randomFormattedPercentage = () => randomInt() + "%";