The calculation formula is 72-35+ 1=38. Here, we need to explain according to the order of Arabic numerals and the meaning of the number axis:

In the calculation, 72 out of 72-35 represents a point in mathematics. The position of this point is the end of 7 1 and the beginning of 72. Similarly, 35 represents the end of 34 or the beginning of 35, but 72-35 represents the number between 72 and 35, that is, the end of 35 and the beginning of 72. 35 is omitted here, so +65438 is needed.

Extended data:

First, the characteristics of the number axis in representing numbers:

1, the number axis can visually represent numbers, and the points on the horizontal number axis correspond to real numbers one by one, that is, each real number can be represented by a point on the number axis.

2. Compare the sizes of real numbers, with 0 as the center, and the number on the right is greater than the number on the left.

3. The imaginary number can also be represented by the vertical number axis perpendicular to the horizontal number axis and with the same origin, thus forming a complex plane with the horizontal number axis.

4. Two mutually perpendicular number axes with the same origin can form a plane rectangular coordinate system; Three mutually perpendicular number axes with the same origin can form a spatial rectangular coordinate system to determine the position of an object.

Second, Arabic numerals writing rules

1, the "0" before the decimal point of pure decimal cannot be omitted. Whether it is narrative or chart, the "0" before the decimal point of pure decimal cannot be omitted, and numbers in the formats of ".27, .39" cannot appear.

2. Arabic numerals cannot be used with chinese numerals except "ten thousand", "one hundred million" and Chinese symbols with prefix SI. For example,13 million can be rewritten as13 million, but it cannot be written as13 million.

For numbers with 3, 4 or more digits, three-digit segmentation method should be adopted when writing.