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Right Start D - check numbers (casting out nines)


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Can someone explain the purpose of this exercise to me?  I'm really trying to see the long term significance and failing.

 

For those who aren't sure what I'm talking about, it's explained here: https://rightstartmath.com/what-are-check-numbers/

 

I don't mind enforcing it if it is something that will enhance his understanding of numbers, but the way it's presented it just seems to be a cool trick and he's already resistant to some of their way of doing math anyway (instead of adding reps, he multiplies.  He does most of the math mentally and only scratches notes.  He overthinks problems like 'draw one and a half triangles' because half a triangle is still a triangle.)

 

So.....could we skip this, or is it something that he would benefit from learning?

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Digit sums come in handy when dealing with divisibilty rules. But using them to check your work is also handy. CLE also teaches it, and there are threads here discussing it.

 

That's a good point.  He has yet to come across anything that he can't do mentally, but perhaps we'll shelve it as a skill to bring back out in the future.

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My DD has just learned the value of check numbers.  It was something she didn't want to do before, but now that she is doing multi-step problems it has helped her fix mistakes before getting to the end and then having to redo the whole problem because she didn't know where the mistake occurred. 

 

Once she learned how and why, I didn't require her because it would have been a battle.  Currently, she was tired of having to redo so many problems that she started to use the check numbers on her own.  

 

I think like many tools in RightStart are not needed when the problems are simple, but can really help when they get more complicated or have more parts.  

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I skipped those sections in CLE. I understand the point but I don't care. It seems like unnecessary work for me because it's not that hard to check your work other ways, and if I'm adding up a huge series of numbers IRL, I'm probably going to use a calculator. I'm not even a calculator person, but digit sums don't speak to me. 

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If you're continuing on with Rightstart, check numbers are expected to be used through the next two books. They really help on the multivides.

 

So it's not just a neat trick, it's actually party of the program.

 

Sent from my ONEPLUS A5000 using Tapatalk

 

Thanks.  I'm not sure if we'll continue with the program, but that's another good reason to teach it.  I'm keeping an open mind. Right now he is doing almost only the review pages and scoring 100% on each, and anything that he hasn't learned (like check numbers) we take a few days to go through.  It will depend on how much of the scheduled work we're doing by the end of this book that will decide if he continues with the next level or moves on to something that is more in tune with how he wants to learn.

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We're on our 6th kid starting with A. The oldest 3 have graduated RS from RS A-E (we opted not to use RS-G, even though I had it and started it). One's in PreCalc, another in Alg I, one in Pre-A.

 

I have chosen for my 4th, this year, to skip check numbers entirely. It serves no purpose except a nice little trick to check your answers. But none of my oldest 3 ever used this in their journeys, so safe to skip.

 

 

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We loved that section. It was a neat "trick"to math.

Did they NEED it? No.

Is it helpful? Yes. Is it fun? Yes.

Do they still use it/find value in it? Yes.

Can you skip it and not feel guilty? Absolutely.

Even if you stay with the program, it's ok. It'll be referenced, but isn't essential (we've done A-G)

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Well, I just looked ahead to the next LOF book and it teaches casting out nines as well. So I think regardless, I'll have him do the work and then reinforce it with Fred.

 

I'm still not entirely sure why it is necessary, though.

Which LoF is that? We are in check numbers now too. He just did the multiplication 650x2 and he was so MAD he had to use check numbers for the problem he could so easily do in his head. I totally don’t make him when he blurts the answer out faster than I can even think iT! Lol

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Which LoF is that? We are in check numbers now too. He just did the multiplication 650x2 and he was so MAD he had to use check numbers for the problem he could so easily do in his head. I totally don’t make him when he blurts the answer out faster than I can even think iT! Lol

 

That's how mine is!

 

It's LoF Jellybeans.  I bet it'll be just touched on for a few chapters but I haven't looked through it to be sure.  But I'm thinking if anyone can convince him it's a Thing To Know, it'll be Fred.

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