17.99963º=17º+0.99963×60'=17º+59.9778‘=17º+59‘+0.9778×60"=17º+59'+58.668"=17º59'58.668"
度、分、秒之间是60进制。17°不用说了。0.99963°*60=59.9778'0.9778'*60=58.668"所以,17.99963º=17°59'58.668"