Unorganized data is raw data.
Example:
Marks of 20 students in maths test
11, 4, 27, 18, 18, 3, 24, 22, 11, 22,
18, 11, 18, 7, 29, 18, 11, 6, 29, 11
Suppose we want number of students whose marks in 29.
We will have to search for 29 in the numbers & count it.
What if the number of students are more?
If there are 100 students, the counting will become difficult.
So, we organise the data using tally marks.