The first stroke: start from the middle of the upper edge line to the left, draw a straight line to the lower left, and reach the intersection of the left line and the horizontal center line; Draw a small bend to the right, beyond the horizontal center line; Then turn right down to the middle of the lower left grid and the vertical center line; Then draw a bend to the left, to the middle of the lower sideline; Draw a curve to the left and close the pen slightly lower in the middle of the left line.

The second stroke: start from a lower position than the first stroke, draw a horizontal line to the right, and touch the vertical center line to receive the stroke. Specific writing: from less than half of the upper line, left to the middle corner. Draw a big semicircle above the center line, touch the right line, get off the line and go to the left line. The top is horizontal, a little lower than the upper right line, and touches the line to the right.

The mathematical meaning of extended data "5" is Fibonacci number, which is 2+3, the last of the three adjacent prime numbers in the prime number series, and also the adjacent one in the Fibonacci number series; 5 is also a Perl number. 5 is a natural number between 4 and 6, the third prime number, and the 4th, 8th and10th decimal places of pi.

In Chinese, it is synonymous with "Wu" in Chinese, but different from "Wu". In science, the atomic number of boron is 5, and in the nine squares, 5 is the only number that cannot be changed. People have five senses: sight, hearing, smell, taste and touch.