Anonymous at Wed, 22 May 2024 09:29:29 UTC No. 16187546

I read the question and magically instantly know the answer. What, you can't do that?

Anonymous at Wed, 22 May 2024 09:33:31 UTC No. 16187551

>>16187546
no. how you do it?

Anonymous at Wed, 22 May 2024 09:35:00 UTC No. 16187552

I just memorise all the sums up to 500

Anonymous at Wed, 22 May 2024 09:35:19 UTC No. 16187554

>>16187530
243-87
=(240-80)+(3-7)
=160+(-4)
=156

Anonymous at Wed, 22 May 2024 09:36:42 UTC No. 16187555

>>16187530
Common core is how I do it in my head

Anonymous at Wed, 22 May 2024 09:37:13 UTC No. 16187557

>>16187530
I get how common core works but I'm more comfortable with the "traditional" one

Anonymous at Wed, 22 May 2024 09:44:13 UTC No. 16187568

>>16187530
Trouble with common core is it's actually how everyone who is good at math instinctively does things, but it's all tricks you pick up and need to figure out on your own and can't really be taught. For people who suck at math the idiot-proof general algorithm is best and really it's what the people who are good at math fall back to 75% of the time unless the problem is clearly doable with some faster trick.

Anonymous at Wed, 22 May 2024 09:49:09 UTC No. 16187572

>>16187530
For me, it's lying jogger removal

Anonymous at Wed, 22 May 2024 09:55:43 UTC No. 16187581

>>16187530
24-8=16
3-7=-4
160-4=156

Anonymous at Wed, 22 May 2024 09:57:40 UTC No. 16187583

>>16187530
>how does /sci/ calculate 243-87 in their head?
200-87=113
113+43=156

Anonymous at Wed, 22 May 2024 09:58:13 UTC No. 16187585

>>16187568
good answer

Anonymous at Wed, 22 May 2024 11:01:30 UTC No. 16187657

>>16187530
200-80=120
7-3=4
40-4=36
120+36=156

Anonymous at Wed, 22 May 2024 13:47:52 UTC No. 16187859

bump one of the numbers to something round because I have 12 IQ

243 - 100 (87 +13)

143 + 13

Anonymous at Wed, 22 May 2024 14:53:11 UTC No. 16187964

243 - 87 = 203 - 47 = 200 - 44 = 156

Anonymous at Wed, 22 May 2024 16:45:35 UTC No. 16188125

>>16187530
I do this
87+3=90
240-90= 150
add the remainder 3 and the difference 3 = 156.

Anonymous at Wed, 22 May 2024 17:43:41 UTC No. 16188198

>>16187530
87-43=44
200-44=156