Theory:

We now know to find the mode of a set of data.
 
We arrange the numbers in ascending or descending orders to find the occurrence of a number.
 
What if there are more numbers, and the process of ordering the numbers in ascending or descending orders becomes time-consuming?
 
In such cases, we can use tally marks to mark the number of occurrences.
Example:
Consider the following set of numbers and find its mode.
 
\(5\), \(7\), \(8\), \(2\), \(9\), \(2\), \(4\), \(4\), \(6\), \(3\), \(7\), \(8\), \(9\), \(2\), \(6\), \(4\), \(5\), \(7\), \(6\), \(4\), \(6\), \(3\), \(4\), \(4\), \(8\), \(7\), \(3\), \(1\), \(5\), \(1\), \(4\), \(6\), \(8\)
 
There are \(33\) numbers altogether.
 
Number
Tally marks
Number of occurrences
\(1\)
1235_1.svg
\(2\)
\(2\)
1235_2.svg
\(3\)
\(3\)
1235_2.svg
\(3\)
\(4\)
1235_5.svg
\(7\)
\(5\)
1235_2.svg
\(3\)
\(6\)
1235_4.svg
\(5\)
\(7\)
1235_3.svg
\(4\)
\(8\)
1235_3.svg
\(4\)
\(9\)
1235_1.svg
\(2\)
 
Total
\(33\)
 
From the table formed above, \(4\) repeats itself \(7\) times.
 
Therefore, \(4\) is the mode of this set of data.