When you need to multiply 7*8 do you simply have it memorized, or do you need to add, subtract or otherwise connect it to another math fact that you know better?
That is do you simply think "56" or are there more thoughts that lead to 56?
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Mostly instant memory. But sometimes also `8*(8-1)` = `64 - 8`
@futurebird I memorize just a few, to save my brain storage, so when I need to calculate, I get the closest memorized value and add the remaining. In this example, I get the memoried 7x7=49 and add 7 to get 56
@futurebird I know 8*8 is 64 off the top of my head and then I divide 8/2 to remove the 8th 8 from 64 to get 4. I then subtract 4 to get to 60 and subtract 4 again to get to 56. Don't ask me why. 8/2 is four. It works so don't judge. LOL Don't get me started how I do big numbers.🤭
@futurebird I know it instantly but only because the 7 and 8 tables were the ones I was struggling with the most. So I learnt the intersection. I still don't know the rest though 😅
@futurebird thanks to the early 80s obsession with times able memorisation, that's locked in as an instant response.
But I also have a couple of maths degrees, so can 'play' with the numbers in my head, using other facts and 'checking' my own memory.
Like 7*7 is 49, + 7 and yup, 56.
Or as others have commented, (7*2)*4 or (7*4)*2 also help.
Or 60 = 15 * 4, and 15 is 14+1 = 7*2+1, so 60-4 works too.
I basically never assume my memory is correct, I always error correct/sense check!
@futurebird I had tables memorized until calculators came along. I was crew treasurer of a tree planting crew in 1979, and once I got that little box in my hand, I forgot everything arithmetical except data entry 😅. Away from tech, I get by on fingers and counting by tens. 😬 Algebra is actually a little easier ... I was an English major and realized early on that all complete sentences are formulae, and the enthymemes used for business and political enclosure are just formulae with hidden variables. It's a shell game and we the public are just rubes (in their eyes) that can't do math.
@futurebird
I still tell left from right based on where the windows were in a grade school classroom.
This is also how I tell debits from credits.
@futurebird 7*8 = 5*8+2*8 = 40+16 = 56
@futurebird When I was young and learning multiplication tables, I had trouble with 8 * 7. Mom told me to turn it around, to 7 * 8, and after that I had no problem.
My method. I just know 7x7 is 49. I then add 7.
@futurebird For some odd reason I have managed to keep all of the x *x numbers (all the squares) up to 100 memorized lo these many years. So I just square 7, then add or subtract 7s as required.
@futurebird I knkw 7x7=49 and I add another 7.
Not convinced I do it the same way every time. This time, I relied on having the value of 7-squared memorized then added another 7.
@futurebird I used to remember almost the entire multiplication table when I was at school, but I forgot most of it shortly after the final exams. But I can calculate it as something like 7*8=14*4=28+28=40+16=56
@futurebird I have to rely on 8=2^3 and count 14, 28, 56.