Question

Take the square of every integer between $-20$ and $20$ (including $-20$ and $20$), and write them down on a list. The first few numbers in the list should be $(-20)^2 = 400$, $(-19)^2 = 361$, and $(-18)^2 = 324$. How many different numbers are there on the list

Answer 1

There are 21 distinct numbers on the list

Explanation:

Square of integers between - 20 and 20

-20² = 400

-19² = 361

-18² = 324

-17² = 289

-16² = 256

-15² = 225

-14² = 196

-13² = 169

-12² = 144

-11² = 121

-10² = 100

-9² = 81

-8² = 64

-7² = 49

-6² = 36

-5² = 25

-4² = 16

-3² = 9

-2² = 4

-1² = 1

0² = 0

1² = 1

2² = 4

3² = 9

4² = 16

5² = 25

6² = 36

7² = 49

8² = 64

9² = 81

10² = 100

11² = 121

12² = 144

13² = 169

14² = 196

15² = 225

16² = 256

17² = 289

18² = 324

19² = 361

20² = 400