Find the Day 30 Days from Now: Modulo 7 Math

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Homework Help Overview

The problem involves determining the day of the week that falls 30 days from a given day, which is Monday. The days of the week are represented numerically from 0 (Sunday) to 6 (Saturday), and the solution requires the application of addition modulo 7.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss whether to apply modulo 7 directly to the number of days or to consider the starting day in their calculations. There is uncertainty about whether to include the current day in the count.

Discussion Status

Participants are exploring different interpretations of the problem, particularly regarding the inclusion of the starting day in the count. Some guidance has been provided regarding the mathematical approach, but ambiguity in the wording of the question remains a point of confusion.

Contextual Notes

The phrasing of the question has led to differing interpretations about whether to count the current day as part of the 30 days, which affects the outcome of the calculations.

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Homework Statement


Days of the week are 0 - Sun to 6 - Sat. Today is Monday, use addition modulo 7 to find the day of the week 30 days from now.

Homework Equations

The Attempt at a Solution


0 - Sunday, 1 - Monday, 2 - Tuesday, 3 - Wednesday, 4 - Thursday, 5 - Friday, and 6 - Saturday. Do we just take 30 mod 7 which is equal to 2 and Tuesday would be our day? Or must I add 1 + 2 = 3 so that Wednesday is the day?

Thank you.
 
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ver_mathstats said:

Homework Statement


Number the days of the week from 0 - Sun to 6 - Sat. Today is Monday, use addition modulo 7 to find the day of the week 30 days from now.

Homework Equations

The Attempt at a Solution


0 - Sunday, 1 - Monday, 2 - Tuesday, 3 - Wednesday, 4 - Thursday, 5 - Friday, and 6 - Saturday. Do we just take 30 mod 7 which is equal to 2 and Tuesday would be our day? Or must I add 1 + 2 = 3 so that Wednesday is the day?

Thank you.
You could simply count the 30 days to answer your question.

If today is Monday, then we have day 1. In 30 days we have day 31, which is 3 modulo seven, i.e. Wednesday.
However, if "from now on" means to count today as well, then it's 1+29=30 = 2, Tuesday.

Thus it is more a matter of language than of mathematics. I hate those questions for their notorious ambiguity.
 
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fresh_42 said:
You could simply count the 30 days to answer your question.

If today is Monday, then we have day 1. In 30 days we have day 31, which is 3 modulo seven, i.e. Wednesday.
However, if "from now on" means to count today as well, then it's 1+29=30 = 2, Tuesday.

Thus it is more a matter of language than of mathematics. I hate those questions for their notorious ambiguity.
Yes that's why I'm confused, that's how the question was worded and I wasn't sure if I had to include the Monday or not, when I counted it I got Tuesday but I am still unsure if I must include the Monday. Thank you for the reply however.
 
ver_mathstats said:
Yes that's why I'm confused, that's how the question was worded and I wasn't sure if I had to include the Monday or not, when I counted it I got Tuesday but I am still unsure if I must include the Monday. Thank you for the reply however.
If today is Monday, what day is it one day from now? Did you count Monday? If you did, it would still be Monday one day from now.
 
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