Because of different understanding, I think the primary school mathematics cycle generally does not need+1 day or-1 day.

For example, put two red beads, two white beads and five black beads on a rope in turn, and repeat this. If you count from the beginning to 5 1, what color is this?

Analysis: This is a repeated cycle of 2+2+5=9 (pieces).

Solution: 5 1 ÷ (2+2+5) = 5...6.

This repeated cycle is 5, and then the sixth cycle only wears 6. According to the cycle, the sixth bead should be black.

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If it meets+1, it should be a leap year, with 365 days plus one day in a year.

For example, June 2008 1 day is Sunday. June 2009 1 What day is it?

(365+1)/7 = 52 ... June 2, 20091is Tuesday.

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If you encounter-1, it should be a number without a period, like a decimal.

For example: 0. 1253253253 ... What is the 50th decimal place?

(50-1)/3 =16 ...1The 50th decimal place is 2.

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To sum up, the total length of the period should be considered, not+1 or-1 of the period itself.

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How did you copy me downstairs?