Analysis: first calculate the area of a big square, then according to the square area formula, the side length x is the arithmetic square root of the area, and then solve it by "pinch point method"; Cut two small squares with a side length of 2 into a big square. The area of this big square is 2? ×2=8,2.828? =7.997584,2.829? =8.00324, so the approximate value of x with two decimal places is about 2.83.

Related information:

There is an approximate problem when using the divisor, that is, the number of digits after a divisor is rounded, that is, the place where the divisor is accurate. From the first non-zero number on the left to the exact number, all numbers are called "significant numbers" of this value.

In actual calculation, there are different requirements for accuracy, generally speaking, it can be "to which place is accurate" or "to keep a few digits" or "to keep a few significant digits". Unless otherwise specified, the rounding principle shall be followed.