Tính hợp lí nếu có thể :
a) 1987 - 200 . 8 + 1005 : 5
b) [ 1200 - ( 42 - 2.3 ) 3 ] : 40
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a, 1987 - 200 .8 +1005 : 5
= 1987 - 1600 + 201
=387 + 201
=588
b, 3687 + 9541 +6313
=19 541
c,248 : {[(368+232):120-3]+122}+2006
=248 :{[600:100-3]+122}+2006
=248 :{[6-3]+122}+2006
=248:{2+122}+2006
=248:124+2006
=2+2006
=2008
1)...=135+65+360+40+24=200+400+24=624
2)...=(8.125).(4.25)=1000.100=100000
4)...= (467+433)+(238+762)+3465=990+1000+3465=5455
5)...=129.(172-73+1)=129.100=12900
6)...=205-(1200-(16-6)3):40=205-(1200-1000):40=205-200:40=205-5=200
a) 2345 − 1000 : [19-2(21-18) 2 ]=2345-1000:1=1345
b) 205 − [ 1200 − ( 4 2 − 2.3 ) 3 ]=205-( 1200 − 1000 ) = 5
a: \(=23\cdot100+300=2600\)
b: \(=300:\left(4+6\right)-25=30-25=5\)
b: =453+64-879+510
=149
c: =-800+1267-987-978-67+1987
=-800+1200+1000-978
=1400-978
=422
a) 23.15 -[115-(12-5)2 ]
= 23.15 -[115-36]
= 8.15 -79
= 120-79
=41
b)5.[(85 - 35 : 7) :8 + 90 ] - 50
=5 .[80:8+90]-50
=5.100-50
=500-50
=450
c){[261 - ( 36-31)3.2 ]-9}.1001
={[261 - 125.2 ]-9}.1001
={[261 -250 ]-9}.1001
={11-9}.1001
=2.1001
=2002
d)3.102 - [1200 - ( 42 - 2.3)3]
=3.100-[1200 -(16-6)3 ]
=300-[1200-1000]
=300-200
=100
a, \(1987-200.8+1005\div5\)
\(=1987-1600+201\)
\(=387+201\)
\(=588\)
a) 1987 - 200 . 8 + 1005 : 5
= 1987 - 1600 + 201
= 588
b) [ 1200 - ( 42 - 2 . 3 ) 3 ] : 40
= [ 1200 - ( 16 - 6 ) 3 ] : 40
= [ 1200 - 103 ] : 40
= [ 1200 - 1000 ] : 40
= 200 : 40
= 5