TenPoundHammer wrote: ↑Tue Nov 07, 2017 4:28 pm
But if you don't know math, you don't KNOW if counting up to some random number first is "useful"
It's not random. It's the next multiple of 10. Then 100. Then 1000. (Forget about the money example - that's a very specific application of the more general principle.)
Maybe the thing to do is not stress about math as a topic. Focus on other topics, like pop culture. You seem to be pretty good at it.
I clammed up on 2 or 3 entire categories yesterday because I'm bad at pop culture. But I can do math.
TenPoundHammer wrote: ↑Tue Nov 07, 2017 4:28 pm
But if you don't know math, you don't KNOW if counting up to some random number first is "useful".
Yes, and that's the point. You clearly don't understand the math, so asking us how we got our shortcut is (and has been) completely over your head.
Seriously, learn the math and how to do it. This is 2nd grade level stuff we're talking about here. The earlier stuff on the (x-3)^2 was 9th grade level stuff, but it doesn't matter if you don't know how math works.
Also, stop using the word "random" in completely incorrect ways.
CailinGaoilge wrote: ↑Tue Nov 07, 2017 10:36 pm
I'm dyscalculic and useless at maths, but even I know that you would go to 500, and therefore add 28. So 1700-472 = 1228.
CailinGaoilge wrote: ↑Tue Nov 07, 2017 10:36 pm
I'm dyscalculic and useless at maths, but even I know that you would go to 500, and therefore add 28. So 1700-472 = 1228.
HOW?!?!
BECAUSE ONE PLUS ONE ALWAYS EQUALS TWO.
Add the same two numbers over and over, you always always get the same result.
TenPoundHammer wrote: ↑Tue Nov 07, 2017 9:23 pm
I've played with it on a few other problems and never know which number to go to.
Like say 1700-472. What do I add to the 472? Hell if I know.
What's the next multiple of 10 larger than 472? Spoiler
480. So you add 8 to 472 to get to 480.
Then you go to the next multiple of 100 larger than 480. Spoiler
500. You add 20 to 480 to get to 500. Now add 8 (from the previous result) to the 20 from this result and you get 28.
CailinGaolige did a shortcut and went straight from 472 to 500, skipping the 480. That's fine if you can do it. I'm trying to teach it so that you never need to do anything more than 1 digit math. (That, and you need to be able to figure out that 1+9 is basically the same problem as 10+90, which is the same problem as 100+900.)
I'll repeat: These are not random numbers. You're going to the next multiple of 10 (then 100, then 1000) that's larger than your starting number.
CailinGaoilge wrote: ↑Tue Nov 07, 2017 10:36 pm
I'm dyscalculic and useless at maths, but even I know that you would go to 500, and therefore add 28. So 1700-472 = 1228.
HOW?!?!
Because it's the easiest number to go to! Multiples of 100 are easy to work with, and 500 is the nearest one.
Peter the accountant wrote: ↑Tue Nov 07, 2017 10:54 pm
You're going to the next multiple of 10 (then 100, then 1000) that's larger than your starting number.
Why? Can we just answer THAT?
What. Do. I. Add. To. 472. And. Why. That. Number. Specifically.
Peter the accountant wrote: ↑Tue Nov 07, 2017 10:54 pm
You're going to the next multiple of 10 (then 100, then 1000) that's larger than your starting number.
Why? Can we just answer THAT?
What. Do. I. Add. To. 472. And. Why. That. Number. Specifically.
TenPoundHammer wrote: ↑Tue Nov 07, 2017 11:43 pm
Then I still have to slog through 8 + 20 + whatever, which is just making things a billion times more complicated.
You've just flat out stated that 8+20+200+1000 is more complicated than 1700-472.
TenPoundHammer wrote: ↑Tue Nov 07, 2017 11:43 pm
Then I still have to slog through 8 + 20 + whatever, which is just making things a billion times more complicated.
You've just flat out stated that 8+20+200+1000 is more complicated than 1700-472.
Peter the accountant wrote: ↑Tue Nov 07, 2017 10:54 pm
You're going to the next multiple of 10 (then 100, then 1000) that's larger than your starting number.
Why? Can we just answer THAT?
Because we're trying to do the simplest math we can.
What. Do. I. Add. To. 472. And. Why. That. Number. Specifically.
8. Because 8 gets you to the next multiple of 10.
The problem is that the question you asked is the wrong question. The right question to ask is: What is the next multiple of 10 that is larger than 472.
Answer that question, please. What is the next multiple of 10 that is larger than 472.