diff --git a/demos/accessible/index.html b/demos/accessible/index.html
index 5b56668ab..7a409c9c9 100644
--- a/demos/accessible/index.html
+++ b/demos/accessible/index.html
@@ -109,7 +109,9 @@
       <block type="controls_flow_statements"></block>
     </category>
     <category name="Math" colour="230">
-      <block type="math_number" gap="32"></block>
+      <block type="math_number" gap="32">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic">
         <value name="A">
           <block type="math_number">
diff --git a/demos/code/index.html b/demos/code/index.html
index 84a35ab50..3210db5e0 100644
--- a/demos/code/index.html
+++ b/demos/code/index.html
@@ -113,7 +113,9 @@
       <block type="controls_flow_statements"></block>
     </category>
     <category name="%{BKY_CATMATH}" colour="%{BKY_MATH_HUE}">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic">
         <value name="A">
           <shadow type="math_number">
diff --git a/demos/custom-dialogs/index.html b/demos/custom-dialogs/index.html
index 8c3c0aa4b..517ca12b4 100644
--- a/demos/custom-dialogs/index.html
+++ b/demos/custom-dialogs/index.html
@@ -34,7 +34,9 @@
 
   <xml id="toolbox" style="display: none">
     <category name="Inputs" colour="230">
-      <block type="math_number" gap="32"></block>
+      <block type="math_number" gap="32">
+        <field name="NUM">123</field>
+      </block>
       <block type="text"></block>
       <block type="text_prompt_ext">
         <value name="TEXT">
diff --git a/demos/fixed/index.html b/demos/fixed/index.html
index 346732858..ec68625df 100644
--- a/demos/fixed/index.html
+++ b/demos/fixed/index.html
@@ -31,7 +31,9 @@
     <block type="controls_if"></block>
     <block type="logic_compare"></block>
     <block type="controls_repeat_ext"></block>
-    <block type="math_number"></block>
+    <block type="math_number">
+      <field name="NUM">123</field>
+    </block>
     <block type="math_arithmetic"></block>
     <block type="text"></block>
     <block type="text_print"></block>
diff --git a/demos/generator/index.html b/demos/generator/index.html
index c76e1f3e6..b5621842a 100644
--- a/demos/generator/index.html
+++ b/demos/generator/index.html
@@ -52,7 +52,9 @@
       <block type="controls_whileUntil"></block>
     </category>
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
     </category>
diff --git a/demos/graph/index.html b/demos/graph/index.html
index 4732070d9..f8ebcdbe2 100644
--- a/demos/graph/index.html
+++ b/demos/graph/index.html
@@ -59,7 +59,9 @@
 
   <xml id="toolbox" style="display: none">
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic">
         <value name="A">
           <shadow type="math_number">
diff --git a/demos/interpreter/async-execution.html b/demos/interpreter/async-execution.html
index bb9c0a4b6..0bf5f3f2d 100644
--- a/demos/interpreter/async-execution.html
+++ b/demos/interpreter/async-execution.html
@@ -59,7 +59,9 @@
       <block type="controls_whileUntil"></block>
     </category>
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
     </category>
diff --git a/demos/interpreter/step-execution.html b/demos/interpreter/step-execution.html
index c0a3b59f3..8ba01c118 100644
--- a/demos/interpreter/step-execution.html
+++ b/demos/interpreter/step-execution.html
@@ -66,7 +66,9 @@
       <block type="controls_whileUntil"></block>
     </category>
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
     </category>
diff --git a/demos/maxBlocks/index.html b/demos/maxBlocks/index.html
index a4f73b1a1..ff0dc25dd 100644
--- a/demos/maxBlocks/index.html
+++ b/demos/maxBlocks/index.html
@@ -68,7 +68,9 @@
       </block>
     </category>
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
     </category>
diff --git a/demos/minimap/index.html b/demos/minimap/index.html
index 50512d7ca..1e4f34dc7 100644
--- a/demos/minimap/index.html
+++ b/demos/minimap/index.html
@@ -39,7 +39,9 @@
     <block type="controls_if"></block>
     <block type="logic_compare"></block>
     <block type="controls_repeat_ext"></block>
-    <block type="math_number"></block>
+    <block type="math_number">
+      <field name="NUM">123</field>
+    </block>
     <block type="math_arithmetic"></block>
     <block type="text"></block>
     <block type="text_print"></block>
diff --git a/demos/mirror/index.html b/demos/mirror/index.html
index 0098e92df..57254452d 100644
--- a/demos/mirror/index.html
+++ b/demos/mirror/index.html
@@ -41,7 +41,9 @@
     <block type="controls_if"></block>
     <block type="logic_compare"></block>
     <block type="controls_repeat_ext"></block>
-    <block type="math_number"></block>
+    <block type="math_number">
+      <field name="NUM">123</field>
+    </block>
     <block type="math_arithmetic"></block>
     <block type="text"></block>
     <block type="text_print"></block>
diff --git a/demos/resizable/overlay.html b/demos/resizable/overlay.html
index ee2600e04..53529e460 100644
--- a/demos/resizable/overlay.html
+++ b/demos/resizable/overlay.html
@@ -57,7 +57,9 @@
     <block type="controls_if"></block>
     <block type="logic_compare"></block>
     <block type="controls_repeat_ext"></block>
-    <block type="math_number"></block>
+    <block type="math_number">
+      <field name="NUM">123</field>
+    </block>
     <block type="math_arithmetic"></block>
     <block type="text"></block>
     <block type="text_print"></block>
diff --git a/demos/rtl/index.html b/demos/rtl/index.html
index 080e9f864..de911b13e 100644
--- a/demos/rtl/index.html
+++ b/demos/rtl/index.html
@@ -81,7 +81,9 @@
       <block type="controls_flow_statements"></block>
     </category>
     <category name="رياضيات">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
       <block type="math_trig"></block>
diff --git a/demos/storage/index.html b/demos/storage/index.html
index 2c195b8e2..d8d4a0aa1 100644
--- a/demos/storage/index.html
+++ b/demos/storage/index.html
@@ -68,7 +68,9 @@
       <block type="controls_whileUntil"></block>
     </category>
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
     </category>
diff --git a/demos/toolbox/index.html b/demos/toolbox/index.html
index 0e3d7cd3f..df291e008 100644
--- a/demos/toolbox/index.html
+++ b/demos/toolbox/index.html
@@ -78,7 +78,9 @@
       <block type="controls_flow_statements"></block>
     </category>
     <category name="Math">
-      <block type="math_number"></block>
+      <block type="math_number">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic"></block>
       <block type="math_single"></block>
       <block type="math_trig"></block>
diff --git a/tests/multi_playground.html b/tests/multi_playground.html
index ae1a6580d..a9ad9f834 100644
--- a/tests/multi_playground.html
+++ b/tests/multi_playground.html
@@ -202,7 +202,9 @@ h1 {
       <block type="controls_flow_statements"></block>
     </category>
     <category name="Math" colour="230">
-      <block type="math_number" gap="32"></block>
+      <block type="math_number" gap="32">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic">
         <value name="A">
           <shadow type="math_number">
diff --git a/tests/playground.html b/tests/playground.html
index 158ade166..a00de41e8 100644
--- a/tests/playground.html
+++ b/tests/playground.html
@@ -441,7 +441,9 @@ h1 {
       <block type="controls_flow_statements"></block>
     </category>
     <category name="Math" colour="230">
-      <block type="math_number" gap="32"></block>
+      <block type="math_number" gap="32">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic">
         <value name="A">
           <shadow type="math_number">
@@ -768,7 +770,9 @@ h1 {
       <block type="controls_flow_statements"></block>
     </category>
     <category name="Math" colour="230">
-      <block type="math_number" gap="32"></block>
+      <block type="math_number" gap="32">
+        <field name="NUM">123</field>
+      </block>
       <block type="math_arithmetic">
         <value name="A">
           <shadow type="math_number">