| (+-)×4×9 | 2.5×(1.9+1.9+1.9+1.9) |
| 3.64÷4+4.36×25% | 2005× |
| (9+7)÷(+) | ++++++ |
| ++++++++ | 142857÷117+285714÷117+571428÷117. |
(1)(
+
-
)×4×9
=(
+
-
)×36,
=
×36+
×36+
×36,
=6+4+3,
=13;
(2)2.5×(1.9+1.9+1.9+1.9)
=2.5×4×1.9,
=10×1.9,
=19;
(3)3.64÷4+4.36×25%
=3.64×25%+4.36×25%,
=(3.64+4.36)×25%,
=8×25%,
=2;
(4)2005
×
=(2004+1
)×
,
=2004×
+
×
,
=2003+1,
=2004;
(5)(9
+7
)÷(
+
)
=16
÷
,
=13;
(6)
+
+
+
+
+
+
=(1-
)+(1-
)+…+(1-
),
=1+1+1+1+1+1+1-(
+
+…+
),
=7-
,
=7-
,
=6
;
(7)
+
+
+
+
+
+
+
+
=(
++
+
+
)+(+
+
)+(
+
+
),
=
+
+
,
=
+
+
,
=5;
(8)142857÷117+285714÷117+571428÷117.
=142857×
+285714×
+571428×
,
=(142857+285714+571428)×
,
=999999×
,
=8547.