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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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 work with networks a lot, so the powers of 2 are burnt into my brain at this point. 64 is 2 to the power of 6, which by powers laws is 8 squared. 7 x 8 is 8 less than 64. And this explanation took a lot longer than the process takes.
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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?
14, 28, 40, 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
8 * 5 = 40
8 * 2 = 16
Then add them.Yes, every time.
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Off topic, but why does Mastodon offer two things to click on if it's only been edited once?
V confusing.
@futurebird@BenAveling One is the pre-edit version, one is the post-edit version.
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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
14*4 -
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 in elementary school you could at any time (Montessori school) take a times table challenge, and if you got everything right you got I think a stick of gum. This was a big deal to me as Mom was pretty strict about our dental health growing up so we were only allowed sugarfree gum at home
also when we learned them as a class there were songs which also helped. I still remember the tune for the 3 times table song because it was catchy as hell
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For certain types of multiplication... I multiply by 10 (or 100), 1000 and so forth, then subtract the smaller number.
So 7*8 becomes 70 - 2*7 (14) = 56. Obviously I don't do that with such small numbers, but it does work very well when using larger ones.
By converting the answer into two smaller and quicker to answer ones... I get to the answer quicker than some people trying to do the single way.
@Anomnomnomaly @futurebird Yes! Back when my daughter was a wee one, they hade the concept of "10-friends" in school. Memorize 1 for 9, 2 for 8, 3 for 7 and 4 for 6 (5 of couse and, 0 for 10). Thats it! One gets that memorized (backbone level) and methodology for in-head-math will pop up. Beautiful if mentors do credit kids for re-inventing math /methodologies/. I hope this is legible.
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@Anomnomnomaly @futurebird Yes! Back when my daughter was a wee one, they hade the concept of "10-friends" in school. Memorize 1 for 9, 2 for 8, 3 for 7 and 4 for 6 (5 of couse and, 0 for 10). Thats it! One gets that memorized (backbone level) and methodology for in-head-math will pop up. Beautiful if mentors do credit kids for re-inventing math /methodologies/. I hope this is legible.
@Anomnomnomaly @futurebird In other words: we/i claim that it is better NOT to memorize the table of multiplication in favour of thought trains. That helps with understanding. As opposed to using an LLM btw.
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@Anomnomnomaly @futurebird In other words: we/i claim that it is better NOT to memorize the table of multiplication in favour of thought trains. That helps with understanding. As opposed to using an LLM btw.
@Anomnomnomaly @futurebird Theese things get me going...
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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 Nuance: I do have 7x8 memorized, but the answer to the actual question is that I usually pick the closest one I do know and add/subtract, or other similar 'trick'
We listened to musical times table records in 6th grade and a lot of them are still in there.
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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 often factorize somehow and add things up. That way you get to see the numbers, and you can remember your frequently used numbers - not that I'm usually very trained. (lol *grin*)
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Look at the edit history if you want a laugh.
@futurebird that's the mistake the lab rats made when they built the earth
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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@sauropods.win What base are we working in?
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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 This for me changed over the years. At first I just remembered the answer, but after not doing mental math for a while I'd forget. My first shortcut was (8 * 5) + (2 * 8), I learned from a school friend. Later I also learned (7 * 10) - (7 * 2). As I got more familiar with binary, powers of 2 became more intuitive so I also tried (8 *
- 8. But these little tricks are mostly not needed, with a little practice everything comes back, and I revert to memorizing the result again. -
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 mostly directly, but sometimes by comparing it to 7*6 or 8*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 Because I know 7 x 7 is 49, I just 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 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.
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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 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.
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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 7x8 was the only one under 11 that didn't just seem self-evident to 3rd-grade me, so I had to memorize it. It still doesn't have an image or feel for me the way the rest of the 0-10 times tables do...
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@kbm0 @futurebird we went up to 10*10 in West Germany.
We also memorised up to 12 x 12 despite being a country that uses the metric system.
