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diff --git a/date-fns/src/getDecade/index.ts b/date-fns/src/getDecade/index.ts
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+import toDate from '../toDate/index'
+import requiredArgs from '../_lib/requiredArgs/index'
+
+/**
+ * @name getDecade
+ * @category Decade Helpers
+ * @summary Get the decade of the given date.
+ *
+ * @description
+ * Get the decade of 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 given date
+ * @returns {Number} the year of decade
+ * @throws {TypeError} 1 argument required
+ *
+ * @example
+ * // Which decade belongs 27 November 1942?
+ * const result = getDecade(new Date(1942, 10, 27))
+ * //=> 1940
+ */
+export default function getDecade(dirtyDate: Date | number): number {
+  requiredArgs(1, arguments)
+
+  const date = toDate(dirtyDate)
+  const year = date.getFullYear()
+  const decade = Math.floor(year / 10) * 10
+  return decade
+}