b>0</sub> (mod 60),&nbsp;&nbsp;&nbsp; pUN &equiv; <span class="nowrap">R<sub>1</sub></span> (mod 60qA), &nbsp;&nbsp;&nbsp;pN &equiv; <span class="nowrap">R<sub>2</sub></span> (mod q),&nbsp;&nbsp;&nbsp;(2)</p><p>where <span class="nowrap">R<sub>1</sub></span>=<span class="nowrap">qAr<sub>1</sub></span> and <span class="nowrap">R<sub>2</sub></span>=<span class="nowrap">qr<sub>2</sub></span>.</p><p>The second method was adopted since the middle of 7th century, in which the tropical year was simply written as <