37°28′＋44°49′＝(37°+44°)(28'+49')=81°77′=82°17’
108°18′－52°30″＝(108°-52°)17'(60''-30'')=56°17'30''
25°36′×4＝(25°×4)(36'×4)=100°144'=102°24'
40°40′÷3＝(40°÷3)(40'÷3)=(40/3)°(40/3)'=13°33'20''