The decomposition of 625 indicates that 625 = 5× 5× 5 indicates the side length of a square, so it should be 25.
That is, the original width is 25 ÷ 5 = 5, (because the width has been expanded by 5 times to 25, it will be divided by 5 when it is restored).
Similarly, the length is 25× 5 = 125.
This kind of problem is actually a little sensitive to numbers, which can be seen at once. If you really can't see it, decompose 625 and observe it again. The side length is divided into 5×5 and 5×5, that is, 25 (this step is the key! ! ).
I hope this analysis can help you, and I hope you can master it and turn it into your own knowledge. You will do it next time! !