gotcha.

...because that would have been an incorrect formula.

Test failed with month = 1: 0 should equal 1
Test failed with month = 7: 2 should equal 3
Test Passed
Test Passed
Test Passed
Test failed with month = 4: 1 should equal 2
Test failed with month = 2: 0 should equal 1
Test failed with month = 10: 3 should equal 4
Test failed with month = 11: 3 should equal 4
Test failed with month = 8: 2 should equal 3
Test Passed
Test failed with month = 5: 1 should equal 2