diff --git a/app/src/test/java/com/darkempire78/opencalculator/ExpressionUnitTest.kt b/app/src/test/java/com/darkempire78/opencalculator/ExpressionUnitTest.kt
index 0635f9d5..d183748a 100644
--- a/app/src/test/java/com/darkempire78/opencalculator/ExpressionUnitTest.kt
+++ b/app/src/test/java/com/darkempire78/opencalculator/ExpressionUnitTest.kt
@@ -16,113 +16,131 @@ class ExpressionUnitTest {
     private val groupingSeparatorSymbol = DecimalFormatSymbols.getInstance().groupingSeparator.toString()
     @Test
     fun percentage_isCorrect() {
-        var result = calculate("100*95%", false)
+        var result = calculate("100*95%", false).toDouble()
         assertEquals(95.0, result, 0.0)
 
-        result = calculate("(10*10)*95%", false)
+        result = calculate("(10*10)*95%", false).toDouble()
         assertEquals(95.0, result, 0.0)
 
-        result = calculate("100*100%", false)
+        result = calculate("100*100%", false).toDouble()
         assertEquals(100.0, result, 0.0)
 
-        result = calculate("100*100/100*100%", false)
+        result = calculate("100*100/100*100%", false).toDouble()
         assertEquals(100.0, result, 0.0)
 
-        result = calculate("100%10", false)
+        result = calculate("100%10", false).toDouble()
         assertEquals(10.0, result, 0.0)
 
-        result = calculate("10%10%", false)
+        result = calculate("10%10%", false).toDouble()
         assertEquals(0.01, result, 0.0)
 
-        result = calculate("900/10%", false)
+        result = calculate("900/10%", false).toDouble()
         assertEquals(9000.0, result, 0.0)
     }
 
     @Test
     fun addition_isCorrect() {
-        var result = calculate("1+1", false)
+        var result = calculate("1+1", false).toDouble()
         assertEquals(2.0, result, 0.0)
 
-        result = calculate("(1+1)+1", false)
+        result = calculate("(1+1)+1", false).toDouble()
         assertEquals(3.0, result, 0.0)
     }
 
+    @Test
+    fun pow_isCorrect() {
+        var result = calculate("4^3", false).toDouble()
+        assertEquals(64.0, result, 0.0)
+
+        result = calculate("5^-5", false).toDouble()
+        assertEquals(0.00032, result, 0.0)
+    }
+
     @Test
     fun subtraction_isCorrect() {
-        var result = calculate("1-1", false)
+        var result = calculate("1-1", false).toDouble()
         assertEquals(0.0, result, 0.0)
 
-        result = calculate("1-1-1", false)
+        result = calculate("1-1-1", false).toDouble()
         assertEquals(-1.0, result, 0.0)
     }
 
+    @Test
+    fun division_isCorrect() {
+        var result = calculate("0.5/0.01", false).toDouble()
+        assertEquals(50.0, result, 0.0)
+
+        result = calculate("7/2", false).toDouble()
+        assertEquals(3.5, result, 0.0)
+    }
+
     @Test
     fun factorial_isCorrect() {
-        var result = calculate("0!", false)
+        var result = calculate("0!", false).toDouble()
         assertEquals(1.0, result, 0.0)
 
-        result = calculate("5!", false)
+        result = calculate("5!", false).toDouble()
         assertEquals(120.0, result, 0.0)
 
-        result = calculate("10!", false)
+        result = calculate("10!", false).toDouble()
         assertEquals(3628800.0, result, 0.0)
 
-        result = calculate("5!+5!", false)
+        result = calculate("5!+5!", false).toDouble()
         assertEquals(240.0, result, 0.0)
 
-        result = calculate("(3!)!+(3!)!", false)
+        result = calculate("(3!)!+(3!)!", false).toDouble()
         assertEquals(1440.0, result, 0.0)
 
-        result = calculate("(3!)!/(3!)!", false)
+        result = calculate("(3!)!/(3!)!", false).toDouble()
         assertEquals(1.0, result, 0.0)
     }
 
     @Test
     fun sqrt_isCorrect() {
-        var result = calculate("√2^2", false)
+        var result = calculate("√2^2", false).toDouble()
         assertEquals(2.0, result, 0.0)
 
-        result = calculate("√9", false)
+        result = calculate("√9", false).toDouble()
         assertEquals(3.0, result, 0.0)
     }
 
     @Test
     fun trigonometric_functions_isCorrect() {
         // In radians
-        var result = calculate("cos(0)", false)
+        var result = calculate("cos(0)", false).toDouble()
         assertEquals(1.0, result, 0.0)
 
-        result = calculate("1*cos(0)", false)
+        result = calculate("1*cos(0)", false).toDouble()
         assertEquals(1.0, result, 0.0)
 
-        result = calculate("1+cos(0)", false)
+        result = calculate("1+cos(0)", false).toDouble()
         assertEquals(2.0, result, 0.0)
 
-        result = calculate("1-cos(0)", false)
+        result = calculate("1-cos(0)", false).toDouble()
         assertEquals(0.0, result, 0.0)
 
-        result = calculate("2^cos(0)", false)
+        result = calculate("2^cos(0)", false).toDouble()
         assertEquals(2.0, result, 0.0)
 
-        result = calculate("(cos(0))", false)
+        result = calculate("(cos(0))", false).toDouble()
         assertEquals(1.0, result, 0.0)
 
-        result = calculate("cos(2)", false)
+        result = calculate("cos(2)", false).toDouble()
         assertEquals(-0.4161468365471424, result, 0.0)
 
-        result = calculate("tan(pi/2)", false)
-        assertEquals(Double.NaN, result, 0.0)
+        result = calculate("tan(pi/2)", false).toDouble()
+        assertEquals(0.0, result, 0.0) // 0.0 means that it is impossible
 
-        result = calculate("tan(45)", true)
+        result = calculate("tan(45)", true).toDouble()
         assertEquals(0.9999999999999999, result, 0.0)
 
-        result = calculate("sin(220)", true)
+        result = calculate("sin(220)", true).toDouble()
         assertEquals(-0.6427876096865393, result, 0.0)
 
-        result = calculate("sin(5!)", true)
+        result = calculate("sin(5!)", true).toDouble()
         assertEquals(0.8660254037844387, result, 0.0)
 
-        result = calculate("sin(1+1)", true)
+        result = calculate("sin(1+1)", true).toDouble()
         assertEquals(0.03489949670250097, result, 0.0)
     }
 
@@ -135,7 +153,7 @@ class ExpressionUnitTest {
         @BeforeClass
         @JvmStatic fun setup() {
             expression = Expression()
-            calculator = Calculator()
+            calculator = Calculator(10)
         }
     }
 }