diff --git a/core/src/main/kotlin/org/nwapw/abacus/tree/VariableNode.kt b/core/src/main/kotlin/org/nwapw/abacus/tree/VariableNode.kt
new file mode 100644
index 0000000..0bf05c6
--- /dev/null
+++ b/core/src/main/kotlin/org/nwapw/abacus/tree/VariableNode.kt
@@ -0,0 +1,21 @@
+package org.nwapw.abacus.tree
+
+/**
+ * A tree node that holds a placeholder variable.
+ *
+ * This node holds a variable string, and acts similarly to a number,
+ * with the key difference of not actually holding a value at runtime.
+ *
+ * @param variable the actual variable name that this node represents.
+ */
+data class VariableNode(val variable: String) : TreeNode() {
+
+    override fun <T : Any> reduce(reducer: Reducer<T>): T? {
+        return reducer.reduceNode(this)
+    }
+
+    override fun toString(): String {
+        return variable
+    }
+
+}
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