Can you identify the number of marks? They look in the following way:

I - the number 1

II - the number 2

III - the number 3

IIII - the number 4

IIII - the number 5

IIII and I - the number 6

IIII and II - the number 7

IIII and III - the number 8

IIII and IIII - the number 9

IIII and IIII - the number 10.
 

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Using tally (hash) marks is one of the ways of counting. One stick means the number 1, two sticks - the number 2, three sticks - the number 3, four sticks - the number 4. Four sticks crossed out by one (IIII) mean the number 5. If you see four crossed sticks and there are 1, 2, 3, or 4 marks beside it, keep counting from five to the last mark. Or remember this sequence:

IIII - the number 5

IIII and I - the number 6

IIII and II - the number 7

IIII and III - the number 8

IIII and IIII - the number 9

IIII and IIII - the number 10

Note: the stick that crosses out four marks represents one mark as well. Therefore, it turns out that four signs and one crossing mark equal 5. It is convenient to count using tally marks. You may immediately find the number 5, and you do not need to recalculate the crossed sticks. You may also easily find the number 10. This is 5 marks written twice. Now try to define the number using tally (hash) marks.
 

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