Let the side length of the big square assembled first be x, and the side length of the big square assembled later be x+ 1, and the difference of the small squares used is 2x+ 1, and the equation can be obtained:
2x+ 1=32+49
It is easy to solve x=40.
Therefore, the original number of small squares is 40*40+32= 1632.
You can also directly solve the equation:
Let the side length of the first big square be x, and the equation can be obtained:
(x+ 1)^2-x^2=32+49
You can also get x=40, and then use 40*40+32= 1632, over.
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It is equivalent to adding one layer to each adjacent side on the basis of the original square.
* * * Need to add 32+49=8 1 brick, which is twice the original side length+1.
Length of main side =40
Total =40*40+32= 1632 pieces