:=:χ

=

Solution: 2X=72

Solution:1/2x =1/5 *1/4.

Solution: 0.25X= 1.25* 1.6.

X=72/2

1/2X= 1/20

0.25X=2

X=36

X= 1/ 10

X=2/0.25

40:χ=2.5: 15

:χ=4: 16

X=8

Solution 2.5X=600

X=240

Solution: 4X=8X=2

0.625×(8.3-2.5×0. 12)

(2)3÷-÷3

Solution: Original formula =0.625*(8.3-0.3)

Solution: The original formula =3*7/3-3/7* 1/3.

=5

=7- 1/7

5. How to calculate simply? (2 points for each question, ***8 points)

=48/7

( 1)3098+3098×99

(2)6.3×8.7+8.7×3.7

=3098*(99+ 1)

=(6.3+3.7)*8.7

=3098* 100

= 10*8.7

=309800

=87

(3)2.5

×

1.25

×

32

(4) -

=9/7-( 1/3+2/3)

=9/7- 1=2/7

=2.5* 1.25*4*8

=(2.5*4)*( 1.25*8)

= 100

1. "Clever calculation" is fast: 31[10+12+9]

1. Write the number directly.

①

2/9

②

1/6

③

5/2

④

2

⑤

⑥

1

⑦

Seventy two

⑧

5/ 12

⑨

5/3

⑩ 1/ 18

How to calculate the following questions as simple as possible?

①

②

③

④

= 15/ 16*8/3*6/5

= 13/9* 15/26*5/6

=3/5* 1/3+ 1/3*4/5=( 1/2-3/8)*3/4

=

3/2* 1*2

= 1/3*5/2*5/6

= 1/3*(3/5+4/5)

=3

=25/36

=7/ 15

1997× 1996 1996- 1996× 1997 1997=______;

(3) 100+99-98-97+…+4+3-2- 1=______.

I don't know how many, but I did what I did before. Do you want some test papers?

-Good luck with your studies