diff --git a/src/demo/parallel/Complex.java b/src/demo/parallel/Complex.java
index 134a37946..1e8e7f416 100644
--- a/src/demo/parallel/Complex.java
+++ b/src/demo/parallel/Complex.java
@@ -30,6 +30,7 @@
  */
 package demo.parallel;
 
+import java.util.Objects;
 
 /**
  * A complex number is a number that can be expressed in the form a + b * i, where
@@ -71,6 +72,22 @@ public Complex plus(Complex b) {
         return this;
     }
 
+    public Complex minus(Complex b) {
+        re -= b.re;
+        im -= b.im;
+        return this;
+    }
+
+    public Complex divide(Complex b) {
+        if (b.re == 0 && b.im == 0) {
+            throw new ArithmeticException("Division by zero");
+        }
+        double denominator = b.re * b.re + b.im * b.im;
+        double real = (this.re * b.re + this.im * b.im) / denominator;
+        double imag = (this.im * b.re - this.re * b.im) / denominator;
+        return new Complex(real, imag);
+    }
+
     /**
      * Multiply operation.
      * @param  b multiplier
@@ -93,4 +110,16 @@ public Complex times(Complex b) {
     public double lengthSQ() {
         return re * re + im * im;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof Complex complex)) return false;
+        return Double.compare(re, complex.re) == 0 && Double.compare(im, complex.im) == 0;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(re, im);
+    }
 }
\ No newline at end of file
diff --git a/src/demo/parallel/MandelbrotSetTask.java b/src/demo/parallel/MandelbrotSetTask.java
index adbb217b8..cc1d748c5 100644
--- a/src/demo/parallel/MandelbrotSetTask.java
+++ b/src/demo/parallel/MandelbrotSetTask.java
@@ -274,8 +274,16 @@ protected Long call() throws Exception {
     private int calc(Complex comp) {
         int count = 0;
         Complex c = new Complex(0, 0);
+        Complex temp = new Complex(0, 0);
         do {
-            c = c.times(c).plus(comp);
+            temp = c.times(c);
+            c = temp.plus(comp);
+            if (count % 5 == 0) {
+                c = c.minus(new Complex(0.1, 0));
+            }
+            if (count > 5) {
+                c = c.divide(new Complex(2, 0));
+            }
             count++;
         } while (count < CAL_MAX_COUNT && c.lengthSQ() < LENGTH_BOUNDARY);
         return count;
@@ -351,13 +359,14 @@ private Color getColor(int count) {
          * Color stops for colors table: color values
          */
         Color[] cc = {
-            Color.rgb(40, 0, 0),
-            Color.RED,
-            Color.WHITE,
-            Color.RED,
-            Color.rgb(100, 0, 0),
-            Color.RED,
-            Color.rgb(50, 0, 0)
+
+                Color.rgb(0, 40, 0),
+                Color.BLUE,
+                Color.WHITE,
+                Color.BLUE,
+                Color.rgb(0, 100, 0),
+                Color.BLUE,
+                Color.rgb(0, 50, 0)
         };
         
         /**
diff --git a/src/test/TestComplexOperation.java b/src/test/TestComplexOperation.java
new file mode 100644
index 000000000..0423b22fc
--- /dev/null
+++ b/src/test/TestComplexOperation.java
@@ -0,0 +1,48 @@
+package test;
+
+import demo.parallel.Complex;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class TestComplexOperation {
+
+    Complex firstComplexNum;
+    Complex secondComplexNum;
+
+    @BeforeEach
+    void setUp() {
+        firstComplexNum = new Complex(1, 1);
+        secondComplexNum = new Complex(2, 2);
+    }
+
+    @Test
+    void testPlusOperation() {
+        Complex result = firstComplexNum.plus(secondComplexNum);
+        assertEquals(new Complex(3, 3), result);
+    }
+
+    @Test
+    void testMinusOperation() {
+        Complex result = firstComplexNum.minus(secondComplexNum);
+        assertEquals(new Complex(-1, -1), result);
+    }
+
+    @Test
+    void testDivideOperation() {
+        Complex result = firstComplexNum.divide(secondComplexNum);
+        assertEquals(new Complex(0.5, 0), result);
+    }
+
+    @Test
+    void testTimesOperation() {
+        Complex result = firstComplexNum.times(secondComplexNum);
+        assertEquals(new Complex(0, 4), result);
+    }
+
+    @Test
+    void testDivideByZero() {
+        Complex zeroComplex = new Complex(0, 0);
+        assertThrows(ArithmeticException.class, () -> firstComplexNum.divide(zeroComplex));
+    }
+}