Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ ¹ ² ³ °
 

You are not logged in. #1 20061213 08:17:34
Cool Subtraction For KidsWARNING: THIS WAY TO DO IT IS ALL BACKWARDS BUT IT WORKS. igloo myrtilles fourmis #2 20061213 08:21:08
Re: Cool Subtraction For KidsHere's another one: igloo myrtilles fourmis #3 20061213 08:26:03
Re: Cool Subtraction For KidsOkay, here's another one. igloo myrtilles fourmis #4 20061213 08:49:24
Re: Cool Subtraction For Kidsi always do my subtraction in a similar way to that Last edited by lucadeltodesco (20061213 08:50:33) The Beginning Of All Things To End. The End Of All Things To Come. #5 20061213 08:51:41
Re: Cool Subtraction For KidsSorry to go a little off topic but I just remembered this trick when I read this post: "In the real world, this would be a problem. But in mathematics, we can just define a place where this problem doesn't exist. So we'll go ahead and do that now..." #6 20061213 09:05:07
Re: Cool Subtraction For KidsLuca, I love it!! Very sweet that you already did it this way, so awesome!! igloo myrtilles fourmis #7 20061213 10:13:12
Re: Cool Subtraction For Kids
i was always taught the carry the 10 sortof method, but i always found it confusing and harder, and i came up with this method myself while i was in early primary school, and since then i havnt found a better method :p The Beginning Of All Things To End. The End Of All Things To Come. #8 20061213 10:55:55
Re: Cool Subtraction For KidsThat's a very interesting way of subtracting. The traditional way is to carry a ten from the left if you need a bigger number, but your way moves a ten from right to left so that the number being subtracted gets smaller. Both work of course, but the top one if more wellknown. Why did the vector cross the road? It wanted to be normal. #9 20061213 16:50:38
Re: Cool Subtraction For Kidssomething usefull when handling money. When giving change you are usually required to subtract varying amounts from nice round numbers such as 2000, 1000, 500 or 100 when doing this, a trick that seems to work for me is to look at the end of the number you are subtracting, and add the first digit that produces 10, after that, its 9 all the way, untill you get to the last, where it becomes one less. Last edited by mikau (20061213 17:04:44) A logarithm is just a misspelled algorithm. #10 20061213 18:22:25
Re: Cool Subtraction For KidsWhen subtracting with numbers, I mainly just find the difference between the two numbers I am using. I have different methods for 3 or more, however. #11 20061213 21:40:41
Re: Cool Subtraction For KidsUm, that's just the definition of subtracting things. There's no reason why you'd do it any other way. If you mean you do it all in one go, then you still actually do the subtracting units with a ten carried if needed and then subtracting tens, it's just that it's in your head and quickly. Why did the vector cross the road? It wanted to be normal. #12 20061213 22:15:20
Re: Cool Subtraction For Kids
Indeed! "The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman #13 20061214 05:05:29
Re: Cool Subtraction For KidsGracias! A logarithm is just a misspelled algorithm. #14 20061214 06:25:30
Re: Cool Subtraction For KidsI hate that borrowing rule. Takes a bit long in my opinion, I stick with my original statement. #15 20061216 02:21:23
Re: Cool Subtraction For KidsDevanté  you still havn't explained your method however. #16 20061216 05:50:31
Re: Cool Subtraction For Kids
Can you please explain further how this works, because I've tested variations such as 29/92 and 95/39 and they don't work... #17 20061216 07:07:07
Re: Cool Subtraction For KidsI think that trick Ricky used is meant to be a joke. If not then do explain! A logarithm is just a misspelled algorithm. #18 20061216 07:20:11
Re: Cool Subtraction For Kids
If you mean that for instance I take 456123 and just count on from 123 to get to 456, then yes, that is what I do. #19 20061217 01:15:12
Re: Cool Subtraction For KidsSeriously? You'd start at 123 and count until you got to 456? That would take you ages and be fairly pointless, considering the triviality of the sum. I'm probably misunderstanding you. Any other way though, and you'd have to do it in more than one step. Why did the vector cross the road? It wanted to be normal. #20 20061217 02:39:23
Re: Cool Subtraction For KidsFor simple sums like 7336, to find the difference I often get lazy with the standard methods and subtract in parts. I would find 7040 then add 3 and 4. #21 20061217 04:52:29
Re: Cool Subtraction For Kids
A bit like number lines. For 456123, I would do: 123 + 300 + 33. #22 20061218 07:13:09
Re: Cool Subtraction For Kids
Now I think I get it to give another example: #23 20061218 18:09:27
Re: Cool Subtraction For KidsYep, that's what I'd do. Last edited by Devanté (20061218 18:11:57) #24 20061221 04:51:48
Re: Cool Subtraction For KidsLet me try an example that combines both luca and mikau knowledge. igloo myrtilles fourmis #25 20061221 07:12:27
Re: Cool Subtraction For Kids123456789 