①11.23-3.4+8.77-6.6
=11.23+8.77-(3.4+6.6)
=20-10
=10;
②5.4÷[0.68÷(1.2-1.03)]
=5.4÷[0.68÷0.17]
=5.4÷4
=1.35;
③(3.24×99+3.24)÷8.1
=[3.24×(99+1)]÷8.1
=324÷8.1
=40;
④(18.4-3.75)÷12.5÷0.8
=14.65÷12.5÷0.8
=14.65÷(12.5×0.8)
=14.65÷10
=1.465;
⑤12.6÷[(4.3-4.12)×35]
=12.6÷[0.18×35]
=12.6÷6.3
=2;
⑥15.76÷4-3.76×0.25
=15.76×
-3.76×1 4
1 4
=(15.76-3.76)×
1 4
=12×
1 4
=3.