diff --git a/packages/core/src/common.ts b/packages/core/src/common.ts
index a06882f..6cf8c41 100644
--- a/packages/core/src/common.ts
+++ b/packages/core/src/common.ts
@@ -6,7 +6,7 @@ type GroupDigits = string;
 /**
  * Group place.
  */
-type GroupPlace = number;
+export type GroupPlace = bigint;
 
 /**
  * Group of digits and its place.
diff --git a/packages/core/src/exponent.ts b/packages/core/src/exponent.ts
index 3d235e9..654a791 100644
--- a/packages/core/src/exponent.ts
+++ b/packages/core/src/exponent.ts
@@ -81,7 +81,7 @@ export class InvalidValueTypeError extends TypeError {
  * @param value - The value to force a sign on.
  * @returns string The value with a sign.
  */
-const forceNumberSign = (value: number | bigint) => {
+const forceNumberSign = (value: bigint) => {
 	const isExponentNegative = value < 0;
 	const exponentValueAbs = isExponentNegative ? -value : value;
 	const exponentSign = isExponentNegative ? DEFAULT_NEGATIVE_SYMBOL : DEFAULT_POSITIVE_SYMBOL;
diff --git a/packages/core/src/systems/en-US/common.ts b/packages/core/src/systems/en-US/common.ts
index bff1878..f8da2b2 100644
--- a/packages/core/src/systems/en-US/common.ts
+++ b/packages/core/src/systems/en-US/common.ts
@@ -19,7 +19,7 @@ export const EXPONENT_DELIMITER = 'e' as const;
 
 export const EMPTY_GROUP_DIGITS = '000' as const;
 
-export const EMPTY_PLACE: Group = [EMPTY_GROUP_DIGITS, 0];
+export const EMPTY_PLACE: Group = [EMPTY_GROUP_DIGITS, BigInt(0)];
 
 /**
  * Ones number names.
diff --git a/packages/core/src/systems/en-US/parse.ts b/packages/core/src/systems/en-US/parse.ts
index 884c679..2fd055f 100644
--- a/packages/core/src/systems/en-US/parse.ts
+++ b/packages/core/src/systems/en-US/parse.ts
@@ -155,14 +155,14 @@ const doParseGroupName = (result: DoParseState): DoParseState => {
 
 const getGroupPlaceFromGroupName = (groupName: string) => {
 	if (groupName === THOUSAND) {
-		return 1;
+		return BigInt(1);
 	}
 
 	const groupNameBase = groupName.replace(ILLION_SUFFIX, '');
 	const specialMillions = MILLIONS_SPECIAL_PREFIXES.findIndex((p) => groupNameBase === p);
 
 	if (specialMillions > -1) {
-		return specialMillions + 1;
+		return BigInt(specialMillions + 1);
 	}
 
 	let result: DoParseState = {
@@ -176,14 +176,14 @@ const getGroupPlaceFromGroupName = (groupName: string) => {
 		result = doParseGroupName(result);
 	} while (!result.done);
 
-	const bigGroupPlace = Number(
+	const bigGroupPlace = BigInt(
 		result.millias
 			.map((s) => s.toString().padStart(3, '0'))
 			.reverse()
 			.join(''),
 	);
 
-	return bigGroupPlace + 1;
+	return bigGroupPlace + BigInt(1);
 };
 
 enum ParseGroupsMode {
@@ -250,7 +250,7 @@ const parseFinal = (acc: ParserState): ParserState => {
 			lastGroup[GROUP_DIGITS_INDEX] = `${lastGroup[GROUP_DIGITS_INDEX].slice(0, 2)}${ones}`;
 		}
 		// We assume last token without parsed place will always be the smallest
-		lastGroup[GROUP_PLACE_INDEX] = 0;
+		lastGroup[GROUP_PLACE_INDEX] = BigInt(0);
 		return {
 			...acc,
 			groups: [...acc.groups.slice(0, -1), lastGroup],
@@ -263,7 +263,7 @@ const parseFinal = (acc: ParserState): ParserState => {
 		if (tens > -1) {
 			lastGroup[GROUP_DIGITS_INDEX] = `${lastGroup[0].slice(0, 1)}${tens}${lastGroup[GROUP_DIGITS_INDEX].slice(2)}`;
 		}
-		lastGroup[GROUP_PLACE_INDEX] = 0;
+		lastGroup[GROUP_PLACE_INDEX] = BigInt(0);
 		return {
 			...acc,
 			groups: [...acc.groups.slice(0, -1), lastGroup],
@@ -299,7 +299,7 @@ const parseTenPlusOnes = (acc: ParserState, token: string): ParserState => {
 			...acc,
 			lastToken: token,
 			mode: ParseGroupsMode.TEN_PLUS_ONES_MODE,
-			groups: [...acc.groups, [`01${tenPlusOnes}`, lastGroup[GROUP_PLACE_INDEX] - 1]],
+			groups: [...acc.groups, [`01${tenPlusOnes}`, lastGroup[GROUP_PLACE_INDEX] - BigInt(1)]],
 		};
 	}
 
@@ -320,7 +320,7 @@ const parseTens = (acc: ParserState, token: string): ParserState => {
 			...acc,
 			lastToken: token,
 			mode: ParseGroupsMode.TENS_MODE,
-			groups: [...acc.groups, [`0${tens}0`, lastGroup[GROUP_PLACE_INDEX] - 1]],
+			groups: [...acc.groups, [`0${tens}0`, lastGroup[GROUP_PLACE_INDEX] - BigInt(1)]],
 		};
 	}
 
@@ -379,14 +379,37 @@ export const parseGroups = (tokens: string[]) => {
 	return groups;
 };
 
+const bigIntMax = (...b: bigint[]) => b.reduce(
+	(previousMax, current) => {
+		if (typeof previousMax === 'undefined') {
+			return current;
+		}
+		return previousMax > current ? previousMax : current;
+	},
+	undefined as bigint | undefined,
+);
+
+const bigIntMin = (...b: bigint[]) => b.reduce(
+	(previousMin, current) => {
+		if (typeof previousMin === 'undefined') {
+			return current;
+		}
+		return previousMin < current ? previousMin : current;
+	},
+	undefined as bigint | undefined,
+);
+
 export const combineGroups = (groups: Group[]) => {
 	const places = groups.map((g) => g[GROUP_PLACE_INDEX]);
-	const maxPlace = Math.max(...places);
-	const minPlace = Math.min(...places);
+	if (places.length < 1) {
+		return '';
+	}
+	const maxPlace = bigIntMax(...places) as bigint;
+	const minPlace = bigIntMin(...places) as bigint;
 	const firstGroup = groups.find((g) => g[GROUP_PLACE_INDEX] === maxPlace) ?? [...EMPTY_PLACE];
 	const firstGroupPlace = firstGroup[GROUP_PLACE_INDEX];
 	const groupsSorted = [];
-	for (let i = maxPlace; i >= minPlace; i -= 1) {
+	for (let i = maxPlace; i >= minPlace; i = BigInt(i) - BigInt(1)) {
 		const thisGroup = groups.find((g) => g[GROUP_PLACE_INDEX] === i) ?? [EMPTY_GROUP_DIGITS, i];
 		groupsSorted.push(thisGroup);
 	}
@@ -401,7 +424,9 @@ export const combineGroups = (groups: Group[]) => {
 	const firstGroupDigits = firstGroup[0];
 	const firstGroupDigitsWithoutZeroes = firstGroupDigits.replace(/^0+/, '');
 	const exponentExtra = firstGroupDigits.length - firstGroupDigitsWithoutZeroes.length;
-	const exponentValue = BigInt((firstGroupPlace * 3) + (2 - exponentExtra));
+	const exponentValue = BigInt(
+		(BigInt(firstGroupPlace) * BigInt(3)) + (BigInt(2) - BigInt(exponentExtra)),
+	);
 	const isExponentNegative = exponentValue < 0;
 	const exponentValueAbs = isExponentNegative ? -exponentValue : exponentValue;
 	const exponentSign = isExponentNegative ? NEGATIVE_SYMBOL : POSITIVE_SYMBOL;
diff --git a/packages/core/src/systems/en-US/stringify.ts b/packages/core/src/systems/en-US/stringify.ts
index e79d906..2c421df 100644
--- a/packages/core/src/systems/en-US/stringify.ts
+++ b/packages/core/src/systems/en-US/stringify.ts
@@ -1,4 +1,9 @@
-import { Group, GROUP_DIGITS_INDEX, GROUP_PLACE_INDEX } from '../../common';
+import {
+	Group,
+	GROUP_DIGITS_INDEX,
+	GROUP_PLACE_INDEX,
+	GroupPlace,
+} from '../../common';
 import { numberToExponential } from '../../exponent';
 import {
 	CENTILLIONS_PREFIXES,
@@ -74,7 +79,7 @@ const makeHundredsName = (hundreds: number, tens: number, ones: number) => {
  * @param milliaCount - Number of millia- groups.
  * @returns string The millions prefix.
  */
-const makeMillionsPrefix = (millions: number, milliaCount: number) => {
+const makeMillionsPrefix = (millions: number, milliaCount: GroupPlace) => {
 	if (milliaCount > 0) {
 		return MILLIONS_PREFIXES[millions] as MillionsPrefix;
 	}
@@ -89,7 +94,7 @@ const makeMillionsPrefix = (millions: number, milliaCount: number) => {
  * @param milliaCount - Number of millia- groups.
  * @returns string The decillions prefix.
  */
-const makeDecillionsPrefix = (decillions: number, millions: number, milliaCount: number) => {
+const makeDecillionsPrefix = (decillions: number, millions: number, milliaCount: GroupPlace) => {
 	if (decillions === 0) {
 		return makeMillionsPrefix(millions, milliaCount);
 	}
@@ -111,7 +116,7 @@ const makeCentillionsPrefix = (
 	centillions: number,
 	decillions: number,
 	millions: number,
-	milliaCount: number,
+	milliaCount: GroupPlace,
 ) => {
 	if (centillions === 0) {
 		return makeDecillionsPrefix(decillions, millions, milliaCount);
@@ -123,23 +128,31 @@ const makeCentillionsPrefix = (
 	return `${hundredsName}${onesPrefix}${decillions > 0 ? tensName : ''}` as const;
 };
 
-const getGroupName = (place: number, shortenMillia: boolean) => {
-	if (place === 0) {
+const repeatString = (s: string, count: GroupPlace) => {
+	let result = '';
+	for (let i = BigInt(0); i < count; i += BigInt(1)) {
+		result += s;
+	}
+	return result;
+};
+
+const getGroupName = (place: GroupPlace, shortenMillia: boolean) => {
+	if (place === BigInt(0)) {
 		return '' as const;
 	}
 
-	if (place === 1) {
+	if (place === BigInt(1)) {
 		return THOUSAND;
 	}
 
-	const bigGroupPlace = place - 1;
+	const bigGroupPlace = place - BigInt(1);
 	const groupGroups = bigGroupPlace
 		.toString()
 		.split('')
 		.reduceRight<Group[]>(
 			(acc, c, i, cc) => {
 				const firstGroup = acc.at(0);
-				const currentPlace = Math.floor((cc.length - i - 1) / 3);
+				const currentPlace = BigInt(Math.floor((cc.length - i - 1) / 3));
 				const newGroup = [EMPTY_GROUP_DIGITS, currentPlace] as Group;
 				if (typeof firstGroup === 'undefined') {
 					newGroup[GROUP_DIGITS_INDEX] = c;
@@ -170,7 +183,7 @@ const getGroupName = (place: number, shortenMillia: boolean) => {
 			const milliaSuffix = (
 				shortenMillia && groupPlace > 1
 					? `${MILLIA_PREFIX}${SHORT_MILLIA_DELIMITER}${groupPlace}`
-					: MILLIA_PREFIX.repeat(groupPlace)
+					: repeatString(MILLIA_PREFIX, groupPlace)
 			);
 
 			if (groupDigits === '001') {
@@ -194,7 +207,7 @@ const getGroupName = (place: number, shortenMillia: boolean) => {
 
 export const makeGroups = (groups: Group[], options?: Record<string, unknown>): string[] => {
 	const filteredGroups = groups.filter(([digits, place]) => (
-		place === 0 || digits !== EMPTY_GROUP_DIGITS
+		place === BigInt(0) || digits !== EMPTY_GROUP_DIGITS
 	));
 
 	return filteredGroups.map(
@@ -232,7 +245,7 @@ export const group = (value: string): Group[] => {
 	const significantDigits = significand.replace(DECIMAL_POINT, '');
 	return significantDigits.split('').reduce<Group[]>(
 		(acc, c, i) => {
-			const currentPlace = Math.floor((exponent - i) / 3);
+			const currentPlace = BigInt(Math.floor((exponent - i) / 3));
 			const lastGroup = acc.at(-1) ?? [EMPTY_GROUP_DIGITS, currentPlace];
 			const currentPlaceInGroup = 2 - ((exponent - i) % 3);
 			if (lastGroup[GROUP_PLACE_INDEX] === currentPlace) {