Intel's lack of documentation stalled MINIX

11.21: news.cyb/adds/doc/Intel's lack of documentation stalled MINIX:
. in an IEEE Computer interview,
[ieeeComputerSociety 2014]
Tanenbaum revealed he designed MINIX when
AT&T closed the source for Unix Version 7
and they could no longer use it
when teaching about the design of an OS.
. but it kept crashing until he heard a rumor
(nothing in the documentation mentioned it)
that the Intel chip when overheating
was causing an interrupt 15.
If his student Robert hadn't revealed the interrupt,
"there would have been no MINIX" he said.

common core math's subtraction

10.20: web.math/common core math/has new subtraction:
businessinsider:
. the new way is realizing a subtraction problem
is asking you to measure the distance between 2 numbers;
You do that, in turn, by measuring the distance between
landmarks (easy, round numbers).

phys.org 2015:
we all do arithmetic like this in our heads all the time.
Say you are buying a scone at a bakery for breakfast
and the total price is US$2.60.
You hand the cashier a $10 bill. How much change do you get?
Now, you do not perform the standard algorithm in your head.
You first note that you'd need another
40 cents to get to the next dollar, making $3,
and then you'd need $7 to get up to $10,
so your change is $7.40.

called the counting up subtraction method.
from the smaller number
count up to the nearest 10, 100, etc;
to that add the largest number's smaller digits.