diff --git a/src/3x5.ts b/src/3x5.ts
index 2d2b410..128bf07 100644
--- a/src/3x5.ts
+++ b/src/3x5.ts
@@ -1,7 +1,8 @@
 import { Card, CardVm, GetField } from "./lib/card";
+import { Expr } from "./lib/expr";
 import { ALL as HTML } from "./lib/html";
 import { parse } from "./parser";
-import { runNoctl, Vm } from "./vm";
+import { runNoctl } from "./vm";
 import { AsHtml, AsText, TextPiece } from "./words";
 
 /**
@@ -119,7 +120,7 @@ function render() {
 
   const vm: CardVm = {
     mode: "render",
-    commands: { ...HTML, get: GetField },
+    commands: { ...HTML, get: GetField, expr: Expr },
     output: "",
     card: theCard,
   };
diff --git a/src/lib/expr.ts b/src/lib/expr.ts
new file mode 100644
index 0000000..59e01f3
--- /dev/null
+++ b/src/lib/expr.ts
@@ -0,0 +1,12 @@
+import { AsText, ProcResult, TextPiece } from "../words";
+
+export function Expr({}, argv: TextPiece[]): ProcResult {
+  const name = argv[0];
+  if ("bare" in name && name.bare == "expr") {
+    // being called as [expr ...], not fallback for math
+    argv.splice(0, 1);
+  }
+  return {
+    text: `Will do math to solve ${argv.map(AsText).join(" ")} eventually`,
+  };
+}
diff --git a/src/vm.ts b/src/vm.ts
index e88e725..a187e71 100644
--- a/src/vm.ts
+++ b/src/vm.ts
@@ -59,6 +59,8 @@ function evaluateWord<Context>(
   }
 }
 
+const NUMBER = /^\d+$/;
+
 /**
  * Runs a script in the context of a Noctl state. Potentially mutates the state.
  *
@@ -87,6 +89,8 @@ export function runNoctl<Context>(
     const name = AsText(argv[0]);
     if (name in state.commands) {
       returnWord = state.commands[name](state, argv);
+    } else if (NUMBER.test(name) && "expr" in state.commands) {
+      returnWord = state.commands.expr(state, argv);
     } else {
       returnWord = { error: `Unknown Command: ${name}` };
     }