Question

Tính nhanh giá trị các biểu thức sau:
a) 3.4.25.8.125                   b) 36.63+ 64.63
c) 45.129+ 71.45                d) 26. (43+ 57)+ 74(57 +43)

Answer 1

a) \(3\cdot4\cdot25\cdot8\cdot125\)

\(=\left(125\cdot8\right)\cdot\left(4\cdot25\right)\cdot3\)

\(=1000\cdot100\cdot3\)

\(=300000\)

b) \(36\cdot63+64\cdot663\)

\(=63\cdot\left(36+64\right)\)

\(=63\cdot100\)

\(=6300\)

c) \(45\cdot129+71\cdot129\)

\(=129\cdot\left(129+71\right)\)

\(=129\cdot200\)

\(=25800\)

d) \(26\cdot\left(43+57\right)+74\cdot\left(43+57\right)\)

\(=26\cdot100+74\cdot100\)

\(=2600+7400\)

\(=10100\)

Answer 2

a) 3.4.25.8.125

=3(4.25).(8.125)

=3.100.1000

300000

b) 36.63+ 64.63

=(36+64).63

=100.63

=6300
c) 45.129+ 71.45 

=45.(129+71)

=45.200

=9000              

d) 26. (43+ 57)+ 74(57 +43)

=26.43+26.57 + 74.57 + 74.43

=(26.43+74.43)+(26.57 + 74.57 )

= [43.(26+74)]+[ (26+74).57]

=[43.100]+[100.57]

=4300+5700

= 10000