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?
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@futurebird I did 7*7=49 then added 7, which means 1 less than 7+50 (because ending in 9), resulting in 56.
I did have the multiplication tables memorized in 3 & 4 grade, but I don't really much basic math on a daily basis, and if I do, I generally need to write it down so I can see it. I'm afraid that if I don't make a deliberate effort, I'll be innumerate.
28*2 or 50-14 probably.
Rote - instant recall - memorization of the entire table seems unnecessary to me… once the first half is in your head the rest is available quickly though doubling and adjacent addition/subtraction, but also, because human brains are very inconsistent at it. Personally, I think that flexibility of knowing how to connect relationships across categories and patterns is a huge part of learning to *think* mathematically.
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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?
@futurebird I would say I don’t have it memorized. With the explanation given, I’ll probably use the other math fact that I have 2**n memorized a bit. So 8**2 = 64 then 64-8 = 56.
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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?
@futurebird I know my squares, so I do 7*7 and then add 7.
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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?
@futurebird when I was little I hated math and did everything to get out of doing any math. So I memorized the times tables, which I guess must have seemed easier? Anyway I remember being able to recite the correct answer quickly when it was just numbers, but being stumped when it was a word problem with apples or whatever.
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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?
When I forget my timestables:
7 * 10 = 70.
10-8 = 2.
2 * 7 = 14.
70-14 = 56. -
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?
@futurebird 7×8 = 5×8 + 2×8 = (10×8)/2 + 2×8 = 80/2 + 8 + 8 = 40 + 16 = 56
easy
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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?
@futurebird I remember learning my times tables as a kid. I still have the desk that I learned them at
Some of that has faded - for some reason I always stumble over results in the 40-60 range. So for this one (7*8) I would probably guess 56 or thereabouts, then check my work knowing that 8 squared is 64.
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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?
@futurebird I think 56, then doubt myself and think 5,6,7,8. Yes. 56=7*8
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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?
@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
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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?
i have the benefit of being required early in public school to memorize the 12 by 12 multiplication table
in retrospect, it has stood me in good stead uncountable (see what i did there) times
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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?
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.
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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?
@futurebird I knkw 7x7=49 and I add another 7.
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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?
@futurebird oddly enough, it was exactly this multiplication that tripped me up in front of an entire classroom - for some reason my brain had slipped a notch and decided 8*7 was 63... which, given that i was one of the school's star mathematicians, was a little bit embarrassing
so i picked the 3rd option in honour of that, although i have obviously never forgotten that eight sevens are fifty-six since...
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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?
@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.
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@futurebird I remember learning my times tables as a kid. I still have the desk that I learned them at
Some of that has faded - for some reason I always stumble over results in the 40-60 range. So for this one (7*8) I would probably guess 56 or thereabouts, then check my work knowing that 8 squared is 64.
@MichaelPorter @futurebird I liked the fact that the 9-bys were a palindrome: 18 81, 27 72, 36 63, 45 54.
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clicked other. 7*6 is 42.
@oddtail The Answer is always 42. https://hitchhikers.fandom.com/wiki/42
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@futurebird Edits aside, it's funny how to me 6*7 → 42 at once but 7*6 I need to reorder into 6*7, and same for 8*7 → 56 and 7*8 (note how my "at once" answers don't always have the smaller factor first; it's almost certainly auditory memory).
Yeah, that's how I tried memorizing them, by "chanting". And it's also why I have to "translate" it to Spanish, since I never learned the tables in English. I wish they had bothered to teach us by logic, as I've seen in some other replies. Some of it I've applied by myself over the years, but it was a "painful" self-teaching. I hope they teach it differently now.
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@futurebird Numbers below about 200 form a grid of products in my head because I've been thinking about number theory and discrete factorization for nearly 40 years, so for me 7*8 being 56 is just like, duh, what else would it be.
Similar. I describe it as "I have a lot of friends among the small integers'.
Like, 56 just falls apart into an 8 and a 7, and those line up in formation to display 2^3•7. Numbers dance in my brain.
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@futurebird I remember learning my times tables as a kid. I still have the desk that I learned them at
Some of that has faded - for some reason I always stumble over results in the 40-60 range. So for this one (7*8) I would probably guess 56 or thereabouts, then check my work knowing that 8 squared is 64.
I am similar, only I default to knowing 9x6 is 54 (because 60 - 6), and 56 is 'the other one'. A bit convoluted!
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@passenger @danielaKay @kbm0 @futurebird
Most multiplication tables go up to 12 × 12 regardless of regional measurement systems. There is nothing inherently special about 12 in the imperial system (or whatever non-metric is called). Most clocks go up to 12 and people often refer to dozens.@sloanlance @passenger @danielaKay @kbm0 @futurebird
also learned muitiplication tables to 12 (in England) but was taught nearly exclusively in metric in school (but knowing the 12 times table is at least useful for when you encounter situations where folk are still working in Imperial units (still happens too often with interior design and planning, and also if I'm reading my books about oldtimer British cars and their maintenance)
