4*4= 16

(-4)*(-4)= 16

1.2* 1.2= 1.44

(- 1.2)*(- 1.2)= 1.44

9*9=8 1

(-9)*(-9)=8 1

Root/root symbol ()

7* Root number 7 = 7

Minus 7* minus 7 = 7

Root number 1 1* root number11=1.

Minus sign 1 1* minus sign11=1.

Root number 2 1* Root number 2 1=2 1

Minus 2 1* minus 2 1=2 1.

2.

positive integer

(

15

,69

)

negative integer

(

-5

)

Positive fraction

(

5/4, 0. 1 1, 9.87, 0.99

)

Negative score

(

-2.7,-65438+5/04

)

Positive rational number

(

15,69,5/4,0. 1 1,9.87,0.99

)

unreasonable

(

)

There is no irrational number

The radical sign is an operation symbol, which is opposite to the power. It should be the content of the second year of high school.