add: 只出现一次的数字等

test/math/factorial-trailing-zeroes.test.js

@@ -0,0 +1,6 @@
+import trailingZeroes from '../../src/math/factorial-trailing-zeroes'
+
+test('trailingZeroes', () => {
+  expect(trailingZeroes(3)).toBe(0)
+  expect(trailingZeroes(5)).toBe(1)
+})