diff --git a/core/src/main/kotlin/org/nwapw/abacus/number/NumberUtils.kt b/core/src/main/kotlin/org/nwapw/abacus/number/NumberUtils.kt
new file mode 100644
index 0000000..5503613
--- /dev/null
+++ b/core/src/main/kotlin/org/nwapw/abacus/number/NumberUtils.kt
@@ -0,0 +1,10 @@
+@file:JvmName("NumberUtils")
+package org.nwapw.abacus.number
+
+typealias PromotionFunction = java.util.function.Function<NumberInterface, NumberInterface>
+typealias PromotionPath = List<PromotionFunction>
+typealias NumberClass = Class<NumberInterface>
+
+fun PromotionPath.promote(from: NumberInterface): NumberInterface {
+    return fold(from, { current, function -> function.apply(current) })
+}
\ No newline at end of file