a) 5dm² 21cm²= 5,21dm²
b) 12dm² 3cm²=12,3dm²
c) 247cm² = 2,47dm²
d) 190000mm²= 19dm²
Giải thích
a) 5dm² 21cm²= 5dm² + 0,21dm² = 5,21dm²
b) 12dm² 3cm²= 12dm² + 0,3dm² = 12,3dm²
c) 247cm²= 200cm² + 47cm² = 2dm² + 0,47dm² = 2,47dm²
d) 190000mm²= 1900cm²=19dm²