问题
解答题
(
18
41
2001×
1998÷1998
|
答案
(1))(
+5 6
+7 12
)×482 3
=
×48+5 6
×48+7 12
×48,2 3
=40+28+32,
=100;
(2)18
×3 5
+219 20
×2 5
-19 20 19 20
=(18
+23 5
-1)×2 5
,19 20
=20×
,19 20
=19;
(3)41
×1 3
+513 4
×1 4
+614 5
×1 5 5 6
=(40+1
)×1 3
+(50+13 4
)×1 4
+(60+14 5
)×1 5
,5 6
=40×
+3 4
×4 3
+50×3 4
+4 5
×5 4
+60×4 5
+5 6
×6 5
,5 6
=30+1+40+1+50+1,
=123;
(4)2001×1999 2000
=(2000+1)×
,1999 2000
=2000×
+1×1999 2000
,1999 2000
=1999+
,1999 2000
=1999
;1999 2000
(5)1998÷19981998 1999
=19998÷
,1999×1998+1998 1999
=1998×
,1999 (1999+1)×1998
=
;1999 2000
(6)
+1 2
+1 6
+1 12
+1 20
+1 30
+1 42
.1 56
=
+1 1×2
+1 2×3
+1 3×4
+2 4×5
+1 5×6
+1 6×7 1 7×8
=1-
+1 2
-1 2
+1 3
-1 3
+…+1 4
-1 7
,1 8
=
.7 8