(1)9.1-0.64-0.36
=9.1-(0.64+0.36)
=9.1-1
=8.1;
(2)4×0.8×2.5×12.5
=(4×2.5)×(0.8×12.5)
=10×10
=100;
(3)13×10.2
=13×(10+0.2)
=13×10+13×0.2
=130+2.6
=132.6;
(4)905×99+905
=905×(99+1)
=905×100
=90500;
(5)(
-1 2
+1 3
)÷1 4
1 24
=(
-1 2
+1 3
)×241 4
=
×24-1 2
×24+1 3
×241 4
=12-8+6
=4+6
=10;
(6)
÷[(16 5
+5 3
)×1 5
]15 7
=
÷[16 5
×28 15
]15 7
=
÷416 5
=
.4 5