Kết quả đúng là 495

15 + 25 + 35 + 45 + 55 + 65 + 75 + 85 + 95

= ( 15 + 85 ) + ( 25 + 75 ) + ( 35 + 65 ) +  ( 45 + 55 ) + 95

= 100 + 100 + 100 + 100 + 95

 = 495

     15 + 25 + 35 + 45 + 55 + 65 + 75 + 85

= (15 + 85) + (25 + 75) + (35 + 65) + (45 + 55)

=     100      +    100     +     100     +     100

=                           400

15+25+35+45+55+65+75+85

=(15+85)+(25+75)+(35+65)+(45+55)

=100+100+100+100

=400

= ( 5 + 95 ) + ( 15 + 85 ) + ( 25 + 75 ) + ( 35 + 65 ) + ( 45 + 55 )

= 100 + 100 + 100 + 100 + 100

= 5 x 100

= 500

a: 29+131+237+763

=160+1000

=1160

b: 65+327+15+73

=65+15+327+73

=80+400

=480

c: \(12+54:8-8\)

=12+3-8

=15-8

=7

d: \(45\cdot58+45\cdot42\)

\(=45\cdot\left(58+42\right)\)

\(=45\cdot100=4500\)

e: \(35\cdot34+35\cdot26+40\cdot35\)

\(=35\cdot\left(34+26+40\right)\)

\(=35\cdot100=3500\)

f: \(65\cdot25+65\cdot45+30\cdot65\)

\(=65\cdot\left(25+45+30\right)\)

\(=65\cdot100=6500\)

g: \(750:\left\lbrace32-\left\lbrack2^2+\left(5\cdot3^2-42\right)\right\rbrack\right\rbrace+100\)

\(=\frac{750}{32-\left\lbrack4+5\cdot9-42\right\rbrack}+100=\frac{750}{32-4-45+42}+100\)

\(=\frac{750}{28-3}+100\)

=750:25+100

=30+100

=130

h: \(\left\lbrace630:\left\lbrack16+3\cdot\left(6+3\cdot4\right)\right\rbrack\right\rbrace-1\)

\(=\frac{630}{16+3\cdot\left(6+12\right)}-1=\frac{630}{16+3\cdot18}-1\)

\(=\frac{630}{70}-1\)

=9-1=8

i: \(5871:\left\lbrack928-\left(247-82\right)\cdot5\right\rbrack+2175^0\)

\(=\frac{5871}{928-165\cdot5}+1\)

\(=\frac{5871}{928-825}+1=\frac{5871}{103}+1=57+1=58\)

k: \(375:\left\lbrace32-\left\lbrack4+\left(5\cdot3^2-42\right)\right\rbrack\right\rbrace-14\)

\(=\frac{375}{32-\left\lbrack4+5\cdot9-42\right\rbrack}-14\)

\(=\frac{375}{32-\left\lbrack4+45-42\right\rbrack}-14=\frac{375}{32-\left(4+3\right)}-14=\frac{375}{32-7}-14\)

\(=\frac{375}{25}-14\)

=15-14

=1

585

(15+75)+(20+70)+(25+65)+(30+60)+(35+55)+(40+50)+45
= 90+90+90+90+90+90+45
= 90.6+45
= 540+45=585