diff --git a/src/lib/typescript/functions/index.ts b/src/lib/typescript/functions/index.ts
index 5eb856aad..57cde86bd 100644
--- a/src/lib/typescript/functions/index.ts
+++ b/src/lib/typescript/functions/index.ts
@@ -1,4 +1,4 @@
-export * from './num-length.function';
+export * from './integer-length.function';
 export * from './num-start.function';
 export * from './num-at.function';
 export * from './lcm.function';
diff --git a/src/lib/typescript/functions/integer-length.function.spec.ts b/src/lib/typescript/functions/integer-length.function.spec.ts
new file mode 100644
index 000000000..4d2296f51
--- /dev/null
+++ b/src/lib/typescript/functions/integer-length.function.spec.ts
@@ -0,0 +1,43 @@
+import { expect } from 'chai';
+import { integerLength, integerLengthMath } from './integer-length.function';
+
+describe(`Integer length`, () => {
+	it(`should work with numbers larger than 1`, async () => {
+		expect(integerLength(123)).to.equal(3);
+		expect(integerLength(7653)).to.equal(4);
+		expect(integerLength(85476847)).to.equal(8);
+	});
+
+	it(`should work with 1`, async () => {
+		expect(integerLength(1)).to.equal(1);
+	});
+
+	it(`should work with 0`, async () => {
+		expect(integerLength(0)).to.equal(1);
+	});
+
+	it(`should work with negative numbers`, async () => {
+		expect(integerLength(-34312)).to.equal(5);
+	});
+});
+
+// tslint:disable: deprecation
+describe(`Integer length (Math)`, () => {
+	it(`should work with numbers larger than 1`, async () => {
+		expect(integerLengthMath(123)).to.equal(3);
+		expect(integerLengthMath(7653)).to.equal(4);
+		expect(integerLengthMath(85476847)).to.equal(8);
+	});
+
+	it(`should work with 1`, async () => {
+		expect(integerLengthMath(1)).to.equal(1);
+	});
+
+	it(`should work with 0`, async () => {
+		expect(integerLengthMath(0)).to.equal(0);
+	});
+
+	it(`should work with negative numbers`, async () => {
+		expect(integerLengthMath(-34312)).to.equal(5);
+	});
+});
diff --git a/src/lib/typescript/functions/num-length.function.ts b/src/lib/typescript/functions/integer-length.function.ts
similarity index 99%
rename from src/lib/typescript/functions/num-length.function.ts
rename to src/lib/typescript/functions/integer-length.function.ts
index 0a8fb2b95..9178e32e8 100644
--- a/src/lib/typescript/functions/num-length.function.ts
+++ b/src/lib/typescript/functions/integer-length.function.ts
@@ -2,7 +2,7 @@
  * Returns the length of the integer part of a number.
  */
 export function integerLength(n: number): number {
-	return Math.floor(n).toString().length;
+	return Math.floor(Math.abs(n)).toString().length;
 }
 
 /**
diff --git a/src/lib/typescript/functions/num-at.function.ts b/src/lib/typescript/functions/num-at.function.ts
index f0ed99018..e9879b393 100644
--- a/src/lib/typescript/functions/num-at.function.ts
+++ b/src/lib/typescript/functions/num-at.function.ts
@@ -6,7 +6,7 @@
  * @param n the number of whichs length will be returned
  */
 export function numAt(n: number, p: number): number {
-	return parseInt(n.toString()[p], 10);
+	return parseInt(n.toString()[p], 10) || 0;
 }
 
 /**
diff --git a/src/lib/typescript/functions/num-length.function.spec.ts b/src/lib/typescript/functions/num-length.function.spec.ts
deleted file mode 100644
index e3b966717..000000000
--- a/src/lib/typescript/functions/num-length.function.spec.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-import { expect } from 'chai';
-import { numLength } from './num-length.function';
-
-describe(`Number length`, () => {
-	it(`should work with numbers larger than 1`, async () => {
-		expect(numLength(123)).to.equal(3);
-		expect(numLength(7653)).to.equal(4);
-		expect(numLength(85476847)).to.equal(8);
-	});
-
-	it(`should work with 1`, async () => {
-		expect(numLength(1)).to.equal(1);
-	});
-
-	it(`should work with 0`, async () => {
-		expect(numLength(0)).to.equal(0);
-	});
-
-	it(`should work with negative numbers`, async () => {
-		expect(numLength(-34312)).to.equal(5);
-	});
-});
diff --git a/src/lib/typescript/intcode/intcode.class.ts b/src/lib/typescript/intcode/intcode.class.ts
index efdf5be5c..dfdb2dba3 100644
--- a/src/lib/typescript/intcode/intcode.class.ts
+++ b/src/lib/typescript/intcode/intcode.class.ts
@@ -1,4 +1,4 @@
-import { numAt, numLength } from '@lib/functions';
+import { integerLength, numAt } from '@lib/functions';
 import { Instruction, toInstruction } from './instruction.enum';
 import { Mode } from './mode.enum';
 
@@ -130,7 +130,7 @@ export class IntCodeComputer implements Iterable<number | undefined> {
 	}
 
 	private getMode(v: number, n: number): Mode | undefined {
-		return numAt(v, numLength(v) - n - 3);
+		return numAt(v, integerLength(v) - n - 3);
 	}
 
 	public *[Symbol.iterator](): IterableIterator<number | undefined> {