How do I subtract 12.12 from 20.00 in my head? I am making it harder than it is.
20 - 12 = 8
100 - 12 = 88
Eventually you learn how to handle it adaptively almost automatically. For example if it was 103.00 - 12.12, you could start with the decimal values first, or just recognize what they would do and just do 102 - 12, the decimal.
whenever i see a decimal i know to subtract one more off the integer.
if it's $100 - $25.36 i know automatically it will be $74.xx then i just do the 100-36 in the same way knowing that it will be 70 < xx < 60 cents and get $74.64.
it clicks really fast in my head. it's like the numbers narrow down into what they are, it's hard to explain
Go left to right
2-1 is 1
2.12 is bigger than 0.00 so borrow an extra 1 which makes 0
10-2 is 8
.12 is bigger than .00 so borrow an extra 1 which makes 7
10-1 is 9
.02 is bigger than .00 so borrow an extra 1 which makes 8
10-2 is 8
0 is 0 so the answer is now 07.88
Here's what I like to do in these situations (an informal treatment):
1. Just know what 100, (aka "a dollar"), minus the decimal part (treated as integer part here) is, cold. 1.00 minus "0.12" -> 100 - 12 = 88. -> "0.88". Whatever the difference ("change", in this case) ends up being, it will terminate with 0.88. Store that bit.
Now, this decimal bit (0.88) plus the above decimal bit (0.12) must of course be a dollar, itself. So whatever the integer part (the "dollar" part) happens to be, must add to this dollar, and also to the integer part of the smaller number (12.00) to wind up with 20. That should be easy enough once you get the above "storing" out of the way. 12 + 1 + x = 20, x = 7. Store this bit as well.
You could characterize the third operation as addition in this case, but I prefer to think of it as CONCATENATION: 7 AND-THEN 0.88, PUT-TOGETHER: Now all together
"$12.12 is your total sir, out of $20, hm my display isn't working but it doesn't matter because $7.88 is your change. Here you go, have a nice day, sir."
-t. a cashier in a past life who would actually state these things out loud, which regularly impressed customers (sadly). It was also nice to be able to do because we did in fact have equipment fail once in a while. I also made use of elementary algebra a few times at a service desk when other people were getting stuck.
"Times" in the context of multiplication is a noun, not a verb. "[math]x[/math] times [math]y[/math]" means "[math]y[/math] added [math]x[/math] times". You don't "times" something, you multiply it. Let me guess, you're one of those faggots who refers to fighting someone in a video game as "versing" them because you think "versus" is a verb too, aren't you?
He didn't use it in the form of a noun, still a verb also versus is a preposition
A better example of mistaking a noun for a verb could be "I'll google that" prior to google being added in the dictionary as a verb (on top of having a definition that is a noun)
Maybe I'm wrong. Not that anon.
Like pic related but using only your brain.
>mfw I mentally compute 7.88
>mfw see 8.88
>mfw give the benefit of doubt to sci
>mfw think im the retard.
>not understanding that it is not in fact ignorami as the plural of hippopotamus would have you believe because if its Latin root.
A quick Google search will verify this: "The plural is ignoramuses. Some dictionaries list ignorami as a variation of the plural, but this is a backformation by those who suppose since ignoramus comes from Latin that it would have the Latin –i plural. However, in the original Latin, ignoramus was a verb, not a noun, and would still have the -es plural."
Nice try, here, I'll help you out >>>/reddit/
>be in 4th grade
>everyone is doing mental math
>i have to rely on calculator
>be 25 now
>finally mastering mental math in every day situations
>some mother fucker says something like this
i was way ahead of my time. Id even go as far as saying i was smarter than everyone else back then.
Former high school latinfag here to say stuff on this: ignoramus means 'we do not know' or 'we do not recognize'.
There is no such noun in latin according to what I looked up in my dictionary and the internet.
There are, however, two noun class called o-declension and consonantic declension (other names exist too). A word with o-declension ends in -us if not inflected (nominative singular) and for nominative plural, -us becomes -i. Consonantic declension ends with a consonant for nom. sing. and gets -es attached. So it's not entirely unresonable to think this might have been latin declension, apart from how there is little to find which suggests that this was used as a noun. Seeing how none of us care that there are 6 cases in latin, it's English salvaging foreign cultu- I mean languages.
Sage because irrelevant to natscience & math.