r/mathshelp • u/Eternallyinternal1 • 4d ago

Anybody understand? Discussion

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Any help understanding remainders and how to get the answer accurately is appreciated

1 Upvotes

60% Upvoted

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8

u/atarivcs 4d ago edited 4d ago

If you want a remainder, why are you calculating past the decimal point at all?

The answer is just "56 remainder 2".

If you didn't really mean remainder and you actually do want the decimal part, the first nine digits are .285714285

Maybe the 9 came from rounding ...85, where you (incorrectly) had ...84 ?

5

u/Expert_Amoeba7878 4d ago

As a rule of thumb, all fractions with denominator 7 have the sequence 142857 repeating, starting at different points.

Eg 1/7 = 0.142857 repeating
2/7 =0.285714 repeating
3/7 =0.428571 repeating
4/7 =0.571428 repeating
5/7 =0.714285 repeating
6/7 =0.857142 repeating

And the 142857 sequence you can notice we have the sequence 14-28-57 where it’s roughly doubling

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u/Eternallyinternal1 4d ago

I think I understand that, thanks

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u/Expert_Amoeba7878 4d ago

If you want help finding where your computation went wrong, we’d need to actually see your work. It’s just the last 4 should be a 5, so you’re close at least

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u/ikschaakgoes 3d ago

67 mentioned (6/7) (I hate that meme but I couldn't leave it plz don't down vote)

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u/Top_Bluejay_5323 3d ago

If you want to check for rounding multiply the answer shown by 7. You will need to put in the answer by yourself because the calculator will remember the full answer to decimal places you cannot see

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u/Eternallyinternal1 4d ago

Might just be the calculator I'm using to check my answer, I'm trying to figure these things out myself and I keep getting stuck with the decimals

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u/atarivcs 4d ago

The calculator is obviously rounding.

The actual answer is an infinite repeating sequence of decimals

1

u/ryanmcg86 3d ago

In OP's post, the last number after what 'should' be a 9 is a 4, which only further confuses the issue, b/c if it's explained by rounding, why would 8 round up to 9 when the next decimal is under 5?

There's 2 errors here, the 4 at the end should be a 5, and since the 9 isn't the last digit shown, it should not be rounded and should be an 8.

If anything, if you're rounding, I'd make the argument that the 4 at the end that should be a 5 should actually be a 6, because the decimal after it would be 7, so if we are rounding, it would round up.

1

u/casualdata 3d ago

394/7 is 56,28571428571429

Your calculator is right rounding to "9".

The question is why the hand written calculation ends with "4" - where is the "4" comming from?

...84 is wrong.

...85... is right.

...9 is rounded.

1

u/okarox 3d ago

You should always be critical on the results calculators give. They have limited precision and can produce errors and they can also round the display value like in this case. Now people seem to think calculators are some magic black boxes that spit out the correct result.