a) 67 . 99
= 67 . ( 100 - 1 )
= 67 . 100 - 67
= 6700 - 67
= 6633
b) 998 . 34
= ( 1000 - 2 ) . 34
= 34 . 1000 - 34 . 2
= 34000 - 68
= 33932
a, 67.99
= 67 . (100-1)
= 67.100 - 67
= 6700 - 67
=6633
b, 998.34
= (1000 - 2 ) . 34
= 1000.34 - 2.34
= 34000 - 68
= 33932
*HỌC TỐT*
TK NHÉ ^^ ÊU BỢN