A cumulative frequency table is a table that shows the sum of the frequency of an event and the frequencies of all preceding events. A cumulative frequency table is created by using a frequency table. The table shows the frequency of the scores obtained by 20 students in an exam.

Interval	Frequency
1-25	2
26-50	7
51-75	9
76-100	2

Using these frequencies, the cumulative frequency table is created as follows.

Interval	Frequency	Cumulative Frequency
1-25	2	2
26-50	7	2+7=9
51-75	9	2+7+9 = 18
76-100	2	2+7+9+2 = 20

The cumulative frequency tells the number of data values that are less than or equal to the upper limit of each interval. For example, since the cumulative frequency of 51-75 is 18, there are 18 data values less than or equal to 75. Furthermore, the last cumulative frequency will always equal the total number of data values.