Introduction:
Tally marks are a way of counting and keeping track of numbers. They are simple and efficient marks used to represent numbers visually. Tally marks are commonly used in various fields such as mathematics, statistics, and surveys. Understanding tally marks and their characteristics is essential for accurate counting and representation of numbers.

Explanation:
Tally marks are vertical lines that are drawn in groups to represent numbers. Each tally mark represents one unit or count. The concept of tally marks is based on a simple counting system where every fifth mark is drawn diagonally across the previous four marks. This helps in grouping the tally marks and making it easier to count larger numbers.

Characteristics of Tally Marks:
Tally marks possess the following characteristics:

1. Vertical Lines: Tally marks are always drawn as vertical lines. This means they go straight up and down, perpendicular to the base.

2. Equal Length: All the tally marks in a group are of equal length. This ensures uniformity and makes counting and representation easier.

3. Grouping: After every fourth tally mark, a diagonal slash is drawn across the previous four marks. This grouping helps in counting larger numbers quickly and efficiently.

4. Non-Erasable: Tally marks are typically made using a pen or pencil, and they cannot be easily erased or changed. This makes them reliable for keeping track of counts and numbers.

Example:
Let's say we want to represent the number 7 using tally marks. We would draw six vertical lines with the fifth line having a diagonal slash across the previous four lines. The tally marks would appear as follows:

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In this example, there are six vertical lines representing counts 1 to 6, and the diagonal slash represents the count of 7.

Conclusion:
Tally marks are vertical lines used to represent numbers visually. They are drawn in groups and follow specific rules for grouping and counting. Understanding tally marks is important for accurate representation and counting of numbers.