Poll: the sum(7,9)

[Sarah Reichelt]

> It's this:  How do you mentally process simple addition/subtraction 
> facts?  What actually happens in your brain to elicit 16 when you hear 
> 7+9? (for example)
>
> Why do I ask?
> Three adults I asked today:
> #1: I visually see 7 fingers and 9 fingers and move one finger from 
> the 7 to the 9 to make 10, and 10 and 6 are 16.  But it happens 
> instantaneously. (visual concrete... strategic)
> #2: I simply visualize the 7 and the 9 and "see" a 16 as the missing 
> third party. (visual symbolic... pattern,grouping)
> #3: I roll the tape from my parochial school days: "7 plus 9 is 16."  
> (Actually a Spanish tape, though the person has spoken high-level 
> English for 30 years.)(auditory... linear)
>
What a fascinating question! I had to think for a minute to try and 
analyze how I do that sort of mental arithmetic, but in the end I 
realized what I do.

I seem to have a visual stack that goes up to 10, so I put the 9 into 
stack, then move 1 from the 7 to fill the stack, leaving me with 10 in 
the stack and 6 left over. I guess this is #1 but with more of a 
number-line visualization rather than fingers :-)

HTH,
Sarah