(1)299×101,
=299×(100+1),
=299×100+299,
=29900+299,
=30199;
(2)2
+3
-3
+1
+1
,
=(2+3-3+1+1)+(
+
-
+
+
),
=4+
,
=5
;
(3)24.6×4.6+246×0.44+24.6,
=24.6×4.6+24.6×4.4+24.6,
=24.6×(4.6+4.4+1),
=24.6×10,
=246;
(4)
×27+16×
,
=
×(27+16),
=
×43,
=
;
(5)9900÷25÷4,
=9900÷(25×4),
=9900÷100,
=99;
(6)
×98+
×2,
=
×(98+2),
=
×100,
=75;
(7)11-
-(
×
+
×
),
=11-
-
×(
+
),
=11-
-
×1,
=11-(
+
),
=11-1,
=10;
(8)
+4-(
+
),
=
+4-
-
,
=(
-
)+(4-
),
=3
;
(9)1999+999×999,
=1000+999+999×999,
=1000+999×(1+999),
=1000+999×1000,
=1000+999000,
=1000000;
(10)20.07×1994-19.93×2007,
=20.07×1994-1993×20.07,
=20.07×(1994-1993),
=20.07×1,
=20.07;
(11)0.125×32×2.5,
=0.125×8×4×2.5,
=(0.125×8)×(4×2.5),
=1×10,
=10;
(12)2002×
,
=(2001+1)×
,
=2000+
,
=2000
;
(13)12
-2
×3
÷2
,
=12
-
×
×
,
=12
-3
,
=8
;
(14)0.65×6.4-6.5×0.54+65×9%,
=0.65×6.4-0.65×5.4+0.65×9,
=0.65×(6.4-5.4+9),
=0.65×10,
=6.5;
(15)9999
+999
+99
+9
+4
,
=(9999+999+99+9+4)+(
+
+
+
+
),
=[(10000-1)+(1000-1)+(100-1)+(10-1)+4]+1.6,
=11110-4+4+1.6,
=11110+1.6,
=11111.6;
(16)
×98+2÷
,
=
×98+2×
,
=
×(98+2),
=
×100,
=60;
(17)
×8+
×3-
,
=
×(8+3-1),
=
×10,
=
;
(18)35×
+35×
+35×
,
=35×(
+
+
),
=35×
,
=49;
(19)2.25×1.8+17.5×0.18,
=2.25×1.8+1.75×1.8,
=(2.25+1.75)×1.8,
=4×1.8,
=7.2;
(20)(
+
+
)÷
,
=(
+
+
)×36,
=
×36+
×36+
×36,
=12+6+4,
=22.