### 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 $$1$$ $$2$$ $$2$$ $$3$$ $$3$$ $$3$$ $$4$$ $$7$$ $$5$$ $$3$$ $$6$$ $$5$$ $$7$$ $$4$$ $$8$$ $$4$$ $$9$$ $$2$$ Total $$33$$

From the table formed above, $$4$$ repeats itself $$7$$ times.

Therefore, $$4$$ is the mode of this set of data.