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diff --git a/date-fns/src/lastDayOfDecade/index.ts b/date-fns/src/lastDayOfDecade/index.ts
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+import toDate from '../toDate/index'
+import requiredArgs from '../_lib/requiredArgs/index'
+
+/**
+ * @name lastDayOfDecade
+ * @category Decade Helpers
+ * @summary Return the last day of a decade for the given date.
+ *
+ * @description
+ * Return the last day of a decade for the given date.
+ *
+ * ### v2.0.0 breaking changes:
+ *
+ * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
+ *
+ * @param {Date|Number} date - the original date
+ * @returns {Date} the last day of a decade
+ * @throws {TypeError} 1 argument required
+ *
+ * @example
+ * // The last day of a decade for 21 December 2012 21:12:00:
+ * var result = lastDayOfDecade(new Date(2012, 11, 21, 21, 12, 00))
+ * //=> Wed Dec 31 2019 00:00:00
+ */
+export default function lastDayOfDecade(dirtyDate: Date | number): Date {
+  requiredArgs(1, arguments)
+
+  const date = toDate(dirtyDate)
+  const year = date.getFullYear()
+  const decade = 9 + Math.floor(year / 10) * 10
+  date.setFullYear(decade + 1, 0, 0)
+  date.setHours(0, 0, 0, 0)
+  return date
+}