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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@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...
@futurebird Because I know 7 x 7 is 49, I just add another 7. 🤷🏻♂️
@futurebird mostly directly, but sometimes by comparing it to 7*6 or 8*8
@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 * 7) = 40, 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.
@futurebird This one traumatized me so much I taught all 3 of my kids 'seven eights are fifty six' as a marching cadence when they were toddlers.
@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*)
@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 😂
@futurebird
8 * 5 = 40
8 * 2 = 16
Then add them.
Yes, every time.
14, 28, 40, 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.
@futurebird
I do 7x7 +8, so I voted via other math
@futurebird 56 instantly, but I had Lucky Seven Sampson help me learn it
@futurebird
Instantly, because it was 7x8=56 was the exact calculation that I got wrong at primary school that resulted in me being made to stand up for the rest of the session.
@futurebird I go “8 times 8 is 64” to verify so I guess I have some kind of mechanism with minimal memorization.
@futurebird is it relevant that I though "six seven" even though I'm a millenial? and this one, I do take the result from memory - though I had to reconstruct it from 7*5 (memory) + 7 to reassure myself
@futurebird
Usually 8x8=64-8=56