ONE:

400:

169,196,961:

9+0:

9-8:

10-9:

81-0:

6^0, 8^0, 9^0, 10^0:

6/6:

8/8:

9/9:

Three green matches are relocated to form a '4' in front of the red '0', and one green match is removed.

This forms the number 400, which is a square (20 x 20).

Inspired by Bob's idea of nine being a square number.

]]>Welcome to the forum.

I suspect a catch question. You have 12 matches. I notice that you can make the four letters of NINE (a square number) using 11 matches. One snag: I need to move 4 matches not 3.

Someone will come up with a better solution I'm sure.

Bob

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these 3 square are made from 4 sticks each and empty space between them is 1 stick lenght

Make 1 square from 3 squares by removing 1 stick and moving 3 sticks.