[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.47,0:00:03.51,Default,,0000,0000,0000,,I want to show you a way that,\Nat least, I find more useful to
Dialogue: 0,0:00:04.43,0:00:05.35,Default,,0000,0000,0000,,subtract numbers in my head.
Dialogue: 0,0:00:05.35,0:00:07.92,Default,,0000,0000,0000,,And I do it this way-- it's\Nnot necessarily faster on
Dialogue: 0,0:00:07.93,0:00:10.67,Default,,0000,0000,0000,,paper, but it allows you to\Nremember what you're doing.
Dialogue: 0,0:00:10.67,0:00:12.72,Default,,0000,0000,0000,,Because if you start borrowing\Nand stuff it becomes very hard
Dialogue: 0,0:00:12.72,0:00:14.60,Default,,0000,0000,0000,,to remember what's\Nactually going on.
Dialogue: 0,0:00:14.60,0:00:16.42,Default,,0000,0000,0000,,So let's try out a\Ncouple of problems.
Dialogue: 0,0:00:16.42,0:00:27.34,Default,,0000,0000,0000,,Let's have nine thousand four hundred fifty-six minus seven thousand five hundred eighty-nine.
Dialogue: 0,0:00:27.34,0:00:29.69,Default,,0000,0000,0000,,So the way I do\Nthis in my head.
Dialogue: 0,0:00:29.69,0:00:35.09,Default,,0000,0000,0000,,I say that nine thousand four hundred fifty-six minus\Nseven thousand five hundred eighty-nine-- you have to
Dialogue: 0,0:00:35.09,0:00:36.54,Default,,0000,0000,0000,,remember the two numbers.
Dialogue: 0,0:00:36.54,0:00:40.87,Default,,0000,0000,0000,,So the first thing I do is\NI say, well, what's nine thousand four hundred fifty-six
Dialogue: 0,0:00:40.87,0:00:44.11,Default,,0000,0000,0000,,minus just seven thousand?
Dialogue: 0,0:00:44.11,0:00:48.13,Default,,0000,0000,0000,,That's pretty easy because I\Njust take nine thousand minus seven thousand.
Dialogue: 0,0:00:48.13,0:00:51.58,Default,,0000,0000,0000,,So what I can do is I'll\Ncross out this and I'll
Dialogue: 0,0:00:51.58,0:00:53.65,Default,,0000,0000,0000,,subtract seven thousand from it.
Dialogue: 0,0:00:53.65,0:00:58.09,Default,,0000,0000,0000,,And I'm going to get two thousand four hundred fifty six.
Dialogue: 0,0:00:58.09,0:01:05.41,Default,,0000,0000,0000,,So in my head I tell myself\Nthat nine thousand four hundred fifty-six minus seven thousand five hundred eighty-nine is the
Dialogue: 0,0:01:05.41,0:01:08.67,Default,,0000,0000,0000,,same thing as-- if I just\Nsubtract out the seven thousand--
Dialogue: 0,0:01:08.67,0:01:12.97,Default,,0000,0000,0000,,as two thousand four hundred fifty-six minus five hundred eighty-nine.
Dialogue: 0,0:01:12.98,0:01:15.18,Default,,0000,0000,0000,,I took the seven thousand out\Nof the picture.
Dialogue: 0,0:01:15.18,0:01:18.96,Default,,0000,0000,0000,,I essentially subtracted it\Nfrom both of these numbers.
Dialogue: 0,0:01:18.96,0:01:25.39,Default,,0000,0000,0000,,Now, if I want to do two thousand four hundred fifty-six\Nminus five hundred eighty-nine what I do is I
Dialogue: 0,0:01:25.39,0:01:28.82,Default,,0000,0000,0000,,subtract five hundred from both\Nof these numbers.
Dialogue: 0,0:01:28.82,0:01:31.29,Default,,0000,0000,0000,,So if I subtract five hundred from\Nthis bottom number,
Dialogue: 0,0:01:31.29,0:01:33.16,Default,,0000,0000,0000,,this five will go away.
Dialogue: 0,0:01:33.16,0:01:36.31,Default,,0000,0000,0000,,And if I subtract five hundred from this\Ntop number, what happens?
Dialogue: 0,0:01:36.31,0:01:39.54,Default,,0000,0000,0000,,What's two thousand four hundred fifty-six minus five hundred?
Dialogue: 0,0:01:39.54,0:01:41.15,Default,,0000,0000,0000,,Or an easier way to\Nthink about it?
Dialogue: 0,0:01:41.15,0:01:42.95,Default,,0000,0000,0000,,What's twenty-four minus five?
Dialogue: 0,0:01:42.95,0:01:43.84,Default,,0000,0000,0000,,Well, that's nineteen.
Dialogue: 0,0:01:43.84,0:01:49.03,Default,,0000,0000,0000,,So it's going to be one thousand nine hundred fifty-six.
Dialogue: 0,0:01:49.03,0:01:50.79,Default,,0000,0000,0000,,Let me scroll up a little bit.
Dialogue: 0,0:01:50.79,0:01:52.21,Default,,0000,0000,0000,,So it's one thousand nine hundred fifty six.
Dialogue: 0,0:01:52.21,0:01:57.51,Default,,0000,0000,0000,,So my original problem has now\Nbeen reduced to one thousand nine hundred fifty-six minus eighty-nine.
Dialogue: 0,0:01:57.51,0:02:01.69,Default,,0000,0000,0000,,Now I can subtract eighty from both\Nthat number and that number.
Dialogue: 0,0:02:01.69,0:02:04.74,Default,,0000,0000,0000,,So if I subtract eighty from this\Nbottom number the eight disappears.
Dialogue: 0,0:02:04.74,0:02:07.10,Default,,0000,0000,0000,,Eighty-nine minus eighty is just nine.
Dialogue: 0,0:02:07.10,0:02:09.41,Default,,0000,0000,0000,,And I subtract eighty from this top\Nnumber, I can just think of,
Dialogue: 0,0:02:09.41,0:02:12.38,Default,,0000,0000,0000,,well, what's one hundred ninety-five minus eight?
Dialogue: 0,0:02:12.38,0:02:15.16,Default,,0000,0000,0000,,Well, one hundred ninety-five minus eight, let's see.
Dialogue: 0,0:02:15.16,0:02:17.91,Default,,0000,0000,0000,,Fifteen minus eight is seventeen.
Dialogue: 0,0:02:17.92,0:02:25.14,Default,,0000,0000,0000,,So one hundred ninety-five minus eight is going\Nto be one hundred eighty-seven and then you
Dialogue: 0,0:02:25.14,0:02:26.66,Default,,0000,0000,0000,,still have the six there.
Dialogue: 0,0:02:26.66,0:02:31.91,Default,,0000,0000,0000,,So essentially I said,\None thousand nine hundred fifty-six minus eighty is one thousand eight hundred seventy-six.
Dialogue: 0,0:02:31.91,0:02:35.100,Default,,0000,0000,0000,,And now my problem has been\Nreduced to one thousand eight hundred seventy-six minus nine.
Dialogue: 0,0:02:35.100,0:02:37.45,Default,,0000,0000,0000,,And then we can do\Nthat in our head.
Dialogue: 0,0:02:37.45,0:02:39.68,Default,,0000,0000,0000,,What's seventy-six minus nine?
Dialogue: 0,0:02:39.68,0:02:40.36,Default,,0000,0000,0000,,That's what?
Dialogue: 0,0:02:40.36,0:02:41.66,Default,,0000,0000,0000,,Sixty-seven.
Dialogue: 0,0:02:41.66,0:02:47.79,Default,,0000,0000,0000,,So our final answer is one thousand eight hundred sixty-seven.
Dialogue: 0,0:02:47.79,0:02:50.95,Default,,0000,0000,0000,,And as you can see this isn't\Nnecessarily faster than the way
Dialogue: 0,0:02:50.96,0:02:52.50,Default,,0000,0000,0000,,we've done it in other videos.
Dialogue: 0,0:02:52.50,0:02:54.100,Default,,0000,0000,0000,,But the reason why I like it\Nis that at any stage, I just
Dialogue: 0,0:02:54.100,0:02:56.46,Default,,0000,0000,0000,,have to remember two numbers.
Dialogue: 0,0:02:56.46,0:02:58.84,Default,,0000,0000,0000,,I have to remember my\Nnew top number and my
Dialogue: 0,0:02:58.84,0:03:00.07,Default,,0000,0000,0000,,new bottom number.
Dialogue: 0,0:03:00.07,0:03:03.47,Default,,0000,0000,0000,,My new bottom number is always\Njust some of the leftover
Dialogue: 0,0:03:03.47,0:03:05.16,Default,,0000,0000,0000,,digits of the original\Nbottom number.
Dialogue: 0,0:03:05.16,0:03:07.92,Default,,0000,0000,0000,,So that's how I like to\Ndo things in my head.
Dialogue: 0,0:03:07.92,0:03:10.45,Default,,0000,0000,0000,,Now, just to make sure that we\Ngot the right answer and maybe
Dialogue: 0,0:03:10.45,0:03:13.24,Default,,0000,0000,0000,,to compare and contrast\Na little bit.
Dialogue: 0,0:03:13.24,0:03:15.19,Default,,0000,0000,0000,,Let's do it the\Ntraditional way.
Dialogue: 0,0:03:15.19,0:03:24.91,Default,,0000,0000,0000,,Nine thousand four hundred fifty-six minus seven thousand five hundred eighty-nine.
Dialogue: 0,0:03:24.91,0:03:28.47,Default,,0000,0000,0000,,So the standard way of doing\Nit, I like to do all my
Dialogue: 0,0:03:28.47,0:03:31.31,Default,,0000,0000,0000,,borrowing before I do any of my\Nsubtraction so that I can stay
Dialogue: 0,0:03:31.31,0:03:34.91,Default,,0000,0000,0000,,in my borrowing mode, or you\Ncan think of it as regrouping.
Dialogue: 0,0:03:34.93,0:03:37.79,Default,,0000,0000,0000,,So I look at all of my numbers\Non top and see, are they all
Dialogue: 0,0:03:37.79,0:03:39.33,Default,,0000,0000,0000,,larger than the numbers\Non the bottom?
Dialogue: 0,0:03:39.33,0:03:40.72,Default,,0000,0000,0000,,And I start here at the right.
Dialogue: 0,0:03:40.72,0:03:43.58,Default,,0000,0000,0000,,Six is definitely not larger\Nthan nine, so I have to borrow.
Dialogue: 0,0:03:43.58,0:03:46.63,Default,,0000,0000,0000,,So I'll borrow ten or I'll\Nborrow one from the tens place,
Dialogue: 0,0:03:46.63,0:03:48.13,Default,,0000,0000,0000,,which ends up being ten.
Dialogue: 0,0:03:48.13,0:03:52.100,Default,,0000,0000,0000,,So the six becomes a sixteen and\Nthen the five becomes a four.
Dialogue: 0,0:03:52.100,0:03:54.27,Default,,0000,0000,0000,,Then I go to the tens place.
Dialogue: 0,0:03:54.27,0:03:57.84,Default,,0000,0000,0000,,Four needs to be larger than\Neight, so let me borrow one
Dialogue: 0,0:03:57.86,0:03:59.57,Default,,0000,0000,0000,,from the hundreds place.
Dialogue: 0,0:03:59.57,0:04:03.12,Default,,0000,0000,0000,,So then that four becomes a fourteen\Nor fourteen tens because
Dialogue: 0,0:04:03.12,0:04:04.41,Default,,0000,0000,0000,,we're in the tens place.
Dialogue: 0,0:04:04.41,0:04:07.17,Default,,0000,0000,0000,,And then this four becomes a three.
Dialogue: 0,0:04:07.17,0:04:09.90,Default,,0000,0000,0000,,Now these two columns or places\Nlook good, but right here I
Dialogue: 0,0:04:09.90,0:04:12.20,Default,,0000,0000,0000,,have a three, which is\Nless than a five.
Dialogue: 0,0:04:12.20,0:04:14.40,Default,,0000,0000,0000,,Not cool, so I have\Nto borrow again.
Dialogue: 0,0:04:14.40,0:04:18.82,Default,,0000,0000,0000,,That three becomes a thirteen and\Nthen that nine becomes an eight.
Dialogue: 0,0:04:18.82,0:04:21.63,Default,,0000,0000,0000,,And now I'm ready to subtract.
Dialogue: 0,0:04:21.63,0:04:24.50,Default,,0000,0000,0000,,So you get sixteen minus nine is seven.
Dialogue: 0,0:04:24.50,0:04:27.33,Default,,0000,0000,0000,,Fourteen minus eight is six.
Dialogue: 0,0:04:27.33,0:04:29.44,Default,,0000,0000,0000,,Thirteen minus five is eight.
Dialogue: 0,0:04:29.44,0:04:31.09,Default,,0000,0000,0000,,Eight minus seven is one.
Dialogue: 0,0:04:31.09,0:04:33.91,Default,,0000,0000,0000,,And lucky for us, we\Ngot the right answer.
Dialogue: 0,0:04:33.91,0:04:34.68,Default,,0000,0000,0000,,I want to make it very clear.
Dialogue: 0,0:04:34.68,0:04:36.53,Default,,0000,0000,0000,,There's no better\Nway to do this.
Dialogue: 0,0:04:36.53,0:04:39.68,Default,,0000,0000,0000,,This way is actually kind of\Nlonger and it takes up more
Dialogue: 0,0:04:39.68,0:04:43.12,Default,,0000,0000,0000,,space on your paper than this\Nway was, but this for me,
Dialogue: 0,0:04:43.12,0:04:44.59,Default,,0000,0000,0000,,is very hard to remember.
Dialogue: 0,0:04:44.59,0:04:47.48,Default,,0000,0000,0000,,It's very hard for me to keep\Ntrack of what I borrowed and
Dialogue: 0,0:04:47.48,0:04:50.04,Default,,0000,0000,0000,,what the other number\Nis and et cetera.
Dialogue: 0,0:04:50.04,0:04:52.05,Default,,0000,0000,0000,,But here, at any point\Nin time, I just have to
Dialogue: 0,0:04:52.05,0:04:53.72,Default,,0000,0000,0000,,remember two numbers.
Dialogue: 0,0:04:53.72,0:04:56.64,Default,,0000,0000,0000,,And the two numbers get\Nsimpler every step that I
Dialogue: 0,0:04:56.64,0:04:58.66,Default,,0000,0000,0000,,go through this process.
Dialogue: 0,0:04:58.66,0:05:00.05,Default,,0000,0000,0000,,So this is why I think\Nthat this is a little
Dialogue: 0,0:05:00.05,0:05:01.44,Default,,0000,0000,0000,,bit easier in my head.
Dialogue: 0,0:05:01.44,0:05:03.86,Default,,0000,0000,0000,,But this might be, depending on\Nthe context, easier on paper.
Dialogue: 0,0:05:03.86,0:05:06.59,Default,,0000,0000,0000,,But at least here you didn't\Nhave to borrow or regroup.
Dialogue: 0,0:05:06.59,0:05:21.12,Default,,0000,0000,0000,,Well, hopefully you find\Nthat a little bit useful.