Ta có : 210 =2.3.5.7
150 = 2.3.52
ƯCLN ( 210 , 150 ) = 2 . 3 . 5 =30
=30 chac luon do ban minh la hoc sinh gioi nhat truong hoi lop 5 ay nam ngoai minh thi violympic duoc 300 diem do thi cuoi ki toan va tieng viet deu muoi va con duoc phe la van hay chu dep