Fast version

src/money.ts

@@ -115,19 +115,23 @@ export class Money {
    *
    * pow currently only supports whole numbers.
    */
-  pow(exponent: number): Money {
+  pow(exponent: number | bigint): Money {
 
-    if (!Number.isInteger(exponent)) {
+    if (typeof exponent === 'number' && !Number.isInteger(exponent)) {
       throw new Error('You can currently only use pow() with whole numbers');
     }
 
     if (exponent > 1) {
-      let base:Money = this;
-      for(let i = 1; i < exponent; i++) {
-        base = base.multiply(this);
-      }
-      return base;
+      const resultBig = this.value ** BigInt(exponent);
+      return Money.fromSource(
+        divide(resultBig, PRECISION_M ** (BigInt(exponent)-1n), this.round),
+        this.currency,
+        this.round
+      );
     } else {
+      // This handles the 0, 1 and negative exponent cases.
+      // This uses an iterative approach and is therefore not going to super
+      // fast.
       let base:Money = this;
       for(let i = 1; i > exponent; i--) {
         base = base.divide(this);