Normally we think that there are 52 weeks in a year but there is not accurate. There are 52.14 weeks in a year and some years has 53 weeks because the first week doesn’t always start at 01 Jan. you can check it here: [Week Numbers for 1999 (epochconverter.com)](https://www.epochconverter.com/weeks/1999)  To calculate the week number, you can use this script <code data-gist-id="cc59cf7452e6e53e5b46a2be7b3fd0d9"></code>