How to calculate the arm length?

The measurement method of arm length is as follows:

1. First of all, we should make sure that the arm is stretched, not bent, so that the data we measured can be accurate.

2. Then, we take out the prepared soft ruler, mark it at zero next to the bottom of the neck, and find someone to fix it by hand.

3. Then we need to straighten the soft ruler slowly against the arm, stop when the other end of the soft ruler reaches the palm of your hand, and record the numbers.

4. Finally, we measured it several times to ensure the accuracy of the measured data.

We should make sure to stretch our arms, not bend them.