1.85×82+82× 15 5×289×2 ( 125×25)×4

=(85+ 15)×82 =5×2×289 = 125×(25×4)

= 100×82 = 10×289 = 125× 100

=8200 =2890 = 12500

75×299+75 25×97+25×3 88× 102

=75×299+75× 1 =25×(97+3) =88×( 100+2)

=75×(299+ 1) =25× 100 =88× 100+88×2

=75×300 =2500 =8800+ 176

=22500 =8976

125×88 ( 125+ 17)×8 378+527+73

= 125×(80+8) = 125×8+ 17×8 =900+73

= 125×80+ 125×8 = 1000+ 136 =973

= 10000+ 1000 = 1 136

= 1 1000

167+289+33 58+39+42+6 1 76×25+25×24

= 167+33+289 =(58+42)+(39+6 1) =(76+24)×25

=200+289 = 100+ 100 = 100×25

=489 =200 =2500

2.( 1) How long is the fence in this garden?

(30+25)×2= 1 10 (m)

The fence in this garden is 1 10 meter long.

(2) If there are about 40 tulips per square meter, how many tulips are planted in this garden?

30×25=750 (square meter)

750×40=30000 (tree)

About 30,000 tulips are planted in this garden.

3. Connect the expressions with equal numbers with lines,

102×99 Lian102× (100-1) or (100+2)×99.

102×100-102 Lian102× (100-1)

4. The knowledge of floor tile,

How many tiles are used? 12 yuan for each floor tile, is it enough to prepare 1800 yuan?

158block12×158 =1896 (yuan) 1896 > 1800.

A: 1800 yuan is not enough.

Observe and think:

Two hours is enough: 12×2=24 (km)

4 hours:12× 4 = 48km

Six hours is enough: 12×6=72 (km)

(1) List the formulas of the above problems and observe the changes of the multipliers of each formula. Can you find the changing law of the product?

Two hours is enough: 12×2=24 (km)

4 hours:12× 4 = 48km

Six hours is enough: 12×6=72 (km)

Law of change:

Every n hours, the distance increases by 12N km.

(2) Using the law you found, can you directly write the number of the following formula?

150×20=3000 360×24=8640

150×40=6000 360× 12=4320

150×60=9000 360×6=720

Completion and review

(1). Fill in the form from top to bottom: 500 million, 51million, 54 million, 72.5 million.

(2) found that people's lives are constantly improving. left

2. The first angle is 120 degrees, the second angle is 73 degrees, and the third angle is a triangle. We are 75 degrees, 75 degrees and 30 degrees from the top left to the bottom and then to the right.

leave out

Xi Road and Beijing Road are parallel to each other, and Zhongshan Road and Nanjing Road are parallel to each other.

Xi 'an Road is perpendicular to Nanjing Road or Zhongshan Road, and Beijing Road is perpendicular to Zhongsan Road or Nanjing Road.

5.305×52=3050 624×78=34664 46×589=2534

125×( 12×4)= 12000 35×68+68+68×64= 14208

20 1×24= 16 16 25×(40+4)=4000

75+34+ 125+366=600 8 12+ 197+78= 1077

6. 12×40=480 (yuan)

4800×480=230400 (yuan)

230400 drizzle 250000

A: Not enough.