diff --git a/build/pipelines/templates/run-ui-tests.yaml b/build/pipelines/templates/run-ui-tests.yaml
index 0e2d7656..347a3a8b 100644
--- a/build/pipelines/templates/run-ui-tests.yaml
+++ b/build/pipelines/templates/run-ui-tests.yaml
@@ -47,4 +47,6 @@ jobs:
       vsTestVersion: 16.0
       runSettingsFile: $(Build.ArtifactStagingDirectory)/drop/Release/${{ parameters.platform }}/publish/${{ parameters.runsettingsFileName }}
       platform: ${{ parameters.platform }}
-      configuration: Release
\ No newline at end of file
+      configuration: Release
+      ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
+        testFiltercriteria: Priority=0 
diff --git a/src/CalculatorUITests/StandardModeFunctionalTests.cs b/src/CalculatorUITests/StandardModeFunctionalTests.cs
index 817f7f3d..1ea67916 100644
--- a/src/CalculatorUITests/StandardModeFunctionalTests.cs
+++ b/src/CalculatorUITests/StandardModeFunctionalTests.cs
@@ -57,6 +57,7 @@ namespace CalculatorUITests
 
         #region Smoke Tests
         [TestMethod]
+        [Priority(0)]
         public void SmokeTest_Add()
         {
             page.StandardOperators.NumberPad.Input(3.5);
@@ -67,6 +68,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(0)]
         public void SmokeTest_Add_KeyboardInput()
         {
             page.Header.SendKeys("3+3=");
@@ -74,6 +76,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(0)]
         public void SmokeTest_Subtract()
         {
             page.StandardOperators.NumberPad.Input(4.3);
@@ -84,6 +87,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(0)]
         public void SmokeTest_History()
         {
             page.StandardOperators.NumberPad.Input(-3);
@@ -109,6 +113,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(0)]
         public void SmokeTest_Memory()
         {
             page.StandardOperators.NumberPad.Input(3);
@@ -142,6 +147,7 @@ namespace CalculatorUITests
 
         #region Basic Arthimetic Tests
         [TestMethod]
+        [Priority(1)]
         public void Operator_Reciprocal()
         {
             page.StandardOperators.NumberPad.Input(4);
@@ -150,6 +156,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void Operator_Squared()
         {
             page.StandardOperators.NumberPad.Input(-15.5);
@@ -158,6 +165,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void Operator_SquareRoot()
         {
             page.StandardOperators.NumberPad.Input(144);
@@ -166,6 +174,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void Operator_Percent()
         {
             page.StandardOperators.NumberPad.Input(600);
@@ -177,6 +186,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(0)]
         public void Operator_Delete()
         {
             page.StandardOperators.NumberPad.Input(-12345);
@@ -184,18 +194,8 @@ namespace CalculatorUITests
             Assert.AreEqual("-1,234", page.GetCalculatorResultText());
         }
 
-        // Issue #817: Prefixed multiple zeros
-        [TestMethod]
-        public void Operator_Delete_Prefix_Zeros()
-        {
-            page.StandardOperators.NumberPad.Input(0.1); // To enter decimal point
-            page.StandardOperators.BackSpaceButton.Click();
-            page.StandardOperators.BackSpaceButton.Click();
-            page.StandardOperators.NumberPad.Input(0);
-            Assert.AreEqual("0", page.GetCalculatorResultText());
-        }
-
         [TestMethod]
+        [Priority(0)]
         public void Operator_ClearAll()
         {
             page.StandardOperators.NumberPad.Input(12345);
@@ -206,6 +206,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(0)]
         public void Operator_ClearEntry()
         {
             page.StandardOperators.NumberPad.Input(-12345);
@@ -218,6 +219,7 @@ namespace CalculatorUITests
 
         #region Keyboard Input Tests
         [TestMethod]
+        [Priority(0)]
         public void KeyboardInput_Subtract()
         {
             page.Header.SendKeys("70090-890987=");
@@ -225,6 +227,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void KeyboardInput_Multiply()
         {
             page.Header.SendKeys("-15*3=");
@@ -232,6 +235,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void KeyboardInput_Divide()
         {
             page.Header.SendKeys("26/13=");
@@ -239,6 +243,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void KeyboardInput_SquareRoot()
         {
             page.Header.SendKeys("100@");
@@ -246,6 +251,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void KeyboardInput_Percent()
         {
             page.Header.SendKeys("34+7%=");
@@ -256,6 +262,7 @@ namespace CalculatorUITests
 
         #region Memory Tests
         [TestMethod]
+        [Priority(1)]
         public void Memory_AddTest()
         {
             page.StandardOperators.NumberPad.Input(12);
@@ -271,6 +278,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void Memory_SubtractTest()
         {
             page.StandardOperators.NumberPad.Input(12);
@@ -286,6 +294,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void Memory_RecallTest()
         {
             page.StandardOperators.NumberPad.Input(12);
@@ -301,6 +310,7 @@ namespace CalculatorUITests
         }
 
         [TestMethod]
+        [Priority(1)]
         public void Memory_ClearTest()
         {
             page.StandardOperators.NumberPad.Input(12);