1)
34 x 77 + 286 x 74 - 209 x 74
= 34 x 77 + 74 x (286 - 209 )
= 34 x 77 + 74 x 77
= 77 x ( 34 + 74)
= 77 x 108
= 8316
2)
58 x 75 + 50 x 58 - 58 x 25
=58 x (75+ 50 - 25 )
= 58 x 100
= 5800
3)
123 x 101
=123 x 100 + 1
= 12300 + 1
= 12301
4)
196 x 11
= 169 x 10 + 1
=1690 + 1
= 1691
5)
99 x 34
= (100 - 1) x 34
= 34 x 100 - 34 x 1
= 3400 - 34
= 3366
Cho mình xin CTLHN nhé !!!