3 × 25 × 8 + 4 × 37 × 6 + 2 × 38 × 12
= ( 3 × 8 ) × 25 + ( 4 × 6 ) × 37 + ( 2 × 12 ) × 38
= 24 × 25 + 24 × 37 + 24 × 38
= 24 × ( 25 + 37 + 38 )
= 25 × 100
= 2 500
35 × 34 + 35 × 66 + 65 × 55 + 65 × 45
= 35 × ( 34 + 66 ) + 65 × ( 55 + 45 )
= 35 × 100 + 65 × 100
= 100 × ( 35 + 65 )
= 100 × 100
= 10 000
Cách 1 :
136 × 68 + 16 × 272
= 136 × 2 × 34 + 16 × 272
= 272 × 34 + 16 × 272
= 272 × ( 34 + 16 )
= 272 × 50
= 13 600
Cách 2 :
136 × 68 + 16 × 272
= 136 × 68 + 16 × 2 × 136
= 136 × 68 + 32 × 136
= 136 × ( 68 + 32 )
= 136 × 100
= 13 600
a) \(3.25.8+4.37.6+2.38.12=24.25+24.37+24.38\)
\(=24.\left(25+37+38\right)=24.100=2400\)
b) \(35.34+35.66+65.55+65.45\)
\(=35.\left(34+66\right)+65.\left(55+45\right)=35.100+65.100\)
\(=100.\left(35+65\right)=100.100=10000\)
c) \(136.68+16.272=136.68+32.136\)
\(=136.\left(68+32\right)=136.100=13600\)
p/s: dấu "." là dấu nhân
a. 3 x 25 x 8 + 4 x 37 x 6 + 2 x 38 x 12
= (3 x 8) x 25 + (4 x 6) x 37 + (2 x 12) x 38
= 24 x 25 + 24 x 37 + 24 x 38
= 24 x (25 + 37 + 38)
= 24 x 100
= 2400
b. 35 x 34 + 35 x 66 + 65 x 55 + 65 x 45
= 35 x (34 + 66) + 65 x (55 + 45)
= 35 x 100 + 65 x 100
= 3500 + 6500
= 10000
c. 136 x 68 + 16 x 272
= 136 x 68 + 16 x (2 x 136)
= 136 x 68 + (16 x 2) x 136
= 136 x 68 + 32 x 136
= 136 x (68 + 32)
= 136 x 100
= 13600
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