diff --git a/src/lib/hypermath.spec.ts b/src/lib/hypermath.spec.ts
index aff9d17..d5e1086 100644
--- a/src/lib/hypermath.spec.ts
+++ b/src/lib/hypermath.spec.ts
@@ -19,7 +19,7 @@ describe('HyperMath', () => {
 
     it('should throw an error if the input is invalid', () => {
       expect(() => {
-        HyperMath.multiply('abc', 3);
+        HyperMath.multiply('abc', null);
       }).toThrow('Invalid input');
     });
   });
@@ -69,4 +69,27 @@ describe('HyperMath', () => {
       }).toThrow('Invalid input');
     });
   });
+
+  describe('subtract', () => {
+    it('should subtract two numbers correctly', () => {
+      const result = HyperMath.subtract(7, 5);
+      expect(result).toBe(2);
+    });
+
+    it('should subtract two values with decimals correctly', () => {
+      const result = HyperMath.subtract(8.5, '3.3');
+      expect(result).toBe(5.2);
+    });
+
+    it('should subtract two strings that represent numbers correctly', () => {
+      const result = HyperMath.subtract('9', '5');
+      expect(result).toBe(4);
+    });
+
+    it('should throw an error if the input is invalid', () => {
+      expect(() => {
+        HyperMath.subtract(undefined, 3);
+      }).toThrow('Invalid input');
+    });
+  });
 });
diff --git a/src/lib/hypermath.ts b/src/lib/hypermath.ts
index b67d6dc..4612558 100644
--- a/src/lib/hypermath.ts
+++ b/src/lib/hypermath.ts
@@ -1,5 +1,8 @@
 export class HyperMath {
   static processInput(value: number | string): number {
+    if (!value) {
+      throw new Error('Invalid input');
+    }
     if (typeof value === 'string') {
       if (isNaN(parseInt(value))) {
         throw new Error('Invalid input');
@@ -47,4 +50,17 @@ export class HyperMath {
     result = parseFloat(result.toPrecision(2));
     return result;
   }
+
+  public static subtract(
+    firstValue: number | string,
+    secondValue: number | string,
+  ): number {
+    let a = this.processInput(firstValue);
+    let b = this.processInput(secondValue);
+    let numberOne = parseFloat(a.toPrecision(2));
+    let numberTwo = parseFloat(b.toPrecision(2));
+    let result = numberOne - numberTwo;
+    result = parseFloat(result.toPrecision(2));
+    return result;
+  }
 }