Median: the value in the middle after data sorting. That is, the data is divided into two parts, one part is greater than this value and the other part is less than this value. To find the median, first sort (from small to large), then calculate the serial number of the median and divide the data into odd and even numbers.

Mode: it is the value with the highest frequency in a set of data, that is, mode, and sometimes there are several modes in a set of numbers. For example, the mode of 1, 2, 3, 3 and 4 is 3. For another example, the modes of 1, 2, 2, 3, 3 and 4 are 2 and 3.