2. Cumulative method: measure a plurality of identical minute quantities together, and then divide the measurement results by numbers to obtain the measured values;

3. Substitution method: measure a quantity equal to the measured quantity to replace the measured direct measurement;

4. Translation method: when the length of an object cannot be measured directly (such as the diameter of a ball, the height of a cone, etc.). ), we must find a way to translate to the outside of the object in an equivalent way, and then measure it with a ruler;

5. Rolling method: First measure the circumference of a wheel, let the wheel roll on the measured curve, and record the number of rolling laps. Then multiply the circumference of the wheel by the number of turns to get the length of the curve path.