Matt Collins
Member
- Joined
- Jun 9, 2007
- Messages
- 47,707
23
x 7
___
21
140
___
161
Code:23 x 7 ___ 21 140 ___ 161
2
23
x 7
___
1
12
x34
------
300
60
40
8
------
408
12
x34
------
48
360
------
408
Yes that is box method, but no...
I suspect you're wrong in your recollection and in your podunk town 30 years ago you were actually taught to "carry the 2"
hmm. how would you:
123
x456
??
123
x456
________________
18
12-
6--
15-
10--
5---
12--
8---
4----
________________
56088
I was taught to just shift the digits over before adding them up. replacing the empty spaces with a zero.
eg:
this was before calculators or computers in the class room. when writing em out by hand we just started in a column to the left for the 10s, 100s, 1000s spaces. then treated the empty spaces as a zero. seemed to make sense at the time and it appears to calculate correctly.Code:123 x456 ________________ 18 12- 6-- 15- 10-- 5--- 12-- 8--- 4---- ________________ 56088
That's how I learned it as well, and that is the full show-your-work version of the "long form", which is essentially what the "box form" is doing as well. I'm not seeing anything other than a rebranding here.
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I've long been able to do 3 digit times 3 digit multiplication in my head since 2nd or 3rd grade; I naturally (without ever having been taught) use a mental box method, not a mental long form:
123
x456
---------
40000
8000
5000
1200
600
1000
150
120
18
56088
Is this thread about Jeb Bush or Multiplication? I'm confused.
Is this thread about Jeb Bush or Multiplication? I'm confused.
Just goes to show how uninteresting Jebbie is: the people would rather discuss how to do longform multiplication.