diff --git a/is-integer-number.el b/is-integer-number.el
new file mode 100644
index 0000000..373460d
--- /dev/null
+++ b/is-integer-number.el
@@ -0,0 +1,24 @@
+(require 'seq)
+
+;; Test
+;; Run M-x ert
+
+(ert-deftest test-is-integer-number ()
+  (seq-doseq (i (number-sequence 0 100))
+    (should (is-integer-number i))))
+
+(ert-deftest test-is-integer-number-float ()
+  (seq-doseq (i (number-sequence 0 100))
+    (should (is-integer-number (float i)))))
+
+(ert-deftest test-is-integer-number-float-false ()
+  (seq-doseq (i (number-sequence 0 100))
+    (should (not (is-integer-number (+ i (/ (1+ (random 8)) 10.0)))))))
+
+;; Code
+
+(defun is-integer-number (num)
+  "Return t if NUM is an integer number, nil otherwise."
+  (or (zerop num)
+      (integerp num)
+      (and (floatp num) (equal num (float (truncate num))))))