Divisibility Proof (1 of 2: Sum of 7 consecutive integers)

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We could take consecutive integers as n to n+6, we get the sum as 7n +21 and which is 7(n+3)

abhinavdiddigam
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You can also do it with n, n+1, n+2, n+3, n+4, n+5, n+6. You then get 7n+21 which you can factor to 7(n+3), which again is divisible by 7.

sammyfromsydney
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Eddie, I know you explained why the implication works in both directions verbally but you didn't write anything down to that effect. In an assessment task, what would you be looking for to demonstrate that a student understands the difference between an implication and an equivalence in such a question?

Alge_
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Thanks Eddie Woo. Whoever is watching this no that you are the best.

nicolesclass
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Wow I just realized that the sum of n consecutive numbers is divisible by n if n is odd. Sum of n alternate numbers is divisible by n if n is even

parikshitbarua
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It's funny, when I play Rummikub with my mother and cousins, I use that method to quickly add the value of a sequence of tiles. I just multiply the middle number by how many tiles in the sequence. When they asked me how I knew it would work, I explained the same way, that (n-2)+(n-1)+n+(n+1)+(n+2) is the same as them all being n.

NWAWskeptic
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Sir, greetings from India, , sir which software do you use as whiteboard?

touqeerahmed
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Could u please tell me how to proof that: the sum of every n consecutive integers is always divisible by 4

LiliSolaimani
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Sir could you take lectures on permutations and combinations...please... I know this chapter consists of only basic addition and multiplication but I don't understand how to start the problem and solve... please sir ...I hope you read this and pay some consern...your follower from india..

BronX
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I think that this question is similar to a question from the CEMC Gauss 8 exam

danielkim
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Can we use Euclid's division lemma to prove this? Starting from the numbers 7q+r

gauravkaloria
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8+9+10+11+12+13+14=77, it is also divisible with 7.

vipinchandrabishnoi
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Why in solving equations the majority of mathematicians don’t write ⇔, instead, they might write ⇒?

nawaf_ksa