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## 5th grade

### Course: 5th grade > Unit 3

Lesson 1: Subtracting decimals intro# Estimating decimal subtraction

This video is all about learning to estimate when subtracting decimals. It emphasizes the importance of rounding to the nearest whole number and doing quick mental calculations to get an approximate answer. It's all about getting comfortable with estimation!

## Want to join the conversation?

- Upvote me please if you do thank you for sporting me(26 votes)
- but how do you know if you round up or down?(8 votes)
- You look on the digit on the right of the one you're rounding. If that digit is 5, 6, 7, 8 or 9 you round up. If it's 0, 1, 2, 3, 4 you round down.

That's all, hope that helps.(10 votes)

- i dont even know how to do vis(5 votes)
- let me help you! let me give you a example! so 12.93-6.1 forget the point and whats after it, and then turn it the closest number up so it is 13-6 = you know that right? after you get that bring back the point and whats after it and there you go!(9 votes)

- NEvER GoNa GivE YoU Up NeVeR GOnNA Let YoU DoWN(6 votes)
- How does this work I am having a hard time understanding this(4 votes)
- According to all known laws of aviation, there is no way that a bee should be able to fly. Its wings are too small to get its fat little body off the ground. The bee, of course, flies anyway because bees don't care what humans think is impossible.

Cut to Barry's room, where he's picking out what to wear.

Barry Yellow, black. Yellow, black. Yellow, black. Yellow, black. Ooh, black and yellow! Yeah, let's shake it up a little.

Barry uses honey from a dispenser to style his hair, rinse his mouth, and then applies it to his armpits.

Mom (Janet Benson) (calling from downstairs:) Barry! Breakfast is ready!

Barry: Coming! (phone rings) Oh, hang on a second. (adjusts his antennas into a headset) Hello?

Adam Flayman (on the phone) Barry?

Barry: Adam?

Adam: Can you believe this is happening?

Barry: I can't believe it. I'll pick you up. (hangs up, sharpens his stinger) Lookin' sharp. (flies downstairs)

Mom: Barry, why don't you use the stairs? Your father paid good money for those.

Barry: Sorry. I'm excited.

Dad (Martin Benson): Here's the graduate. We're very proud of you, son. And a perfect report card, all B's.

Mom: Very proud. (touches Barry's hair)

Barry: Ma! I got a thing going here.

Mom: Ah, you got some lint on your fuzz.

Barry: Ow! That's me!

Dad: Wave to us! We'll be in row 118,000.

Barry: Bye! (flies off)

Mom: Barry, I told you, stop flying in the house!

(Barry drives his car to pick up his classmate. Adam's outside his house, reading the Hive Today newspaper. The front page headline reads "FRISBEE HITS HIVE ! Internet Down. Bee: 'I heard sound, then Wham-o!'")

Barry: Hey, Adam.

Adam: Hey, Barry. Is that fuzz gel?

Barry: A little. It's a special day, finally graduating.

Adam: Never thought I'd make it.

Barry: Yeah, three days of grade school, three days of high school.

Adam: Those were so awkward.

Barry: Three days of college. I'm glad I took off one day in the middle and just hitchhiked around the hive.

Adam: You did come back different.

(a bee calls out as they drive past)

Bee: Hi, Barry.

Barry: Hey Artie, growing a mustache? Looks good.

Adam: Hey, did you hear about Frankie?

Barry: Yeah.

Adam: You goin' to his funeral?

Barry: No, I'm not goin' to his funeral. Everybody knows you sting someone, you die. You don't waste it on a squirrel. He was such a hothead.

Adam: Yeah, I guess he could have just gotten out of the way.

(They make various noises as the car goes up and down some hills and does a loop on the road.)

A & B Woah! Oooooooh!

Adam: I love this incorporating an amusement park right into our regular day.

Barry: I guess that's why they say we don't need vacations.

(They arrive, fly in and take their seats.)

Barry: Boy, quite a bit of pomp... under the circumstances.

Barry: Well, Adam, today we are men.

Adam: We are!

Barry: Bee-men.

Adam: Amen!

A & B: Hallelujah! (bumping each other) Aaaaaaaaaaaah!

Announcer: Students, faculty, distinguished bees, please welcome Dean Buzzwell.

Dean Buzzwell walks onto the stage and taps the microphone.

Buzzwell: Welcome, New Hive City graduating class of... (presses a button to change the timer on the podium from9:00to9:15) ...9:15. And that concludes our graduation ceremonies.

(Students cheer, throw their caps into the air as helmets are placed on their heads.)

Buzzwell: And begins your career at Honex Industries!

Barry: Are we gonna pick our jobs today?

Adam: I heard it's just orientation.

Barry: Huh. Woah. Heads up! Here we go.

(The stands for Winger University the students are sitting in begin converting into tram seating.)

Female announcer: Keep your hands and antennas inside the tram at all times. (flies down to go in the tram as it starts moving and repeats it in Spanish:) Mantenga sus manos y antenas dentro del tranvía en todo momento.

Barry: Wonder what it's going to be like?

Adam: A little scary. (he and Barry mimic shivering and making scared noises)

Trudy, the Honex tour guide: Welcome to Honex, a division of Honesco and a part of the Hexagon Group.

Barry: This is it!

everyone: Wow. (tram moves into the factory floor)

Barry: Wow.

Trudy: We know that you, as a bee, have worked your whole life to get to the point where you can work for your whole life. Honey begins when our valiant Pollen Jocks bring the nectar to the hive. Our top-secret formula is automatically color-corrected, scent-adjusted and bubble-contoured into this soothing sweet syrup with its distinctive golden glow you know as...

everyone: Honey!

(Tour guide grabs a beaker of honey as they drive by and tosses it to the group, which bounce it around towards the back.}

Adam: That girl was hot.

Barry: She's my cousin!

Adam: She is?

Barry: Yes, we're all cousins.

Adam: Right. You're right.

Trudy: At Honex, we also constantly strive to improve every aspect of bee existence. These bees are stress-testing a new helmet technology.

(Behind a display window, a bee puts on a helmet, then runs back and forth as levers holding a rolled-up magazine, flyswatter and a shoe move down to try hit him. He is hit by the magazine, dodges the flyswatter, but then hit by the boot and again by all three, followed by being sprayed with aerosol from two cans.(4 votes)- how do you get that avatar(1 vote)

- put the video on 1.75 wow(3 votes)
- Tip: Put playback speed to 1.5 ! :D(2 votes)
- i saw it and it isnt interesting(0 votes)

- this kind of dose not help.(1 vote)
- how does it not help Anl395005? what are you stuck on? may i help you?(2 votes)

## Video transcript

- [Instructor] Alright,
now let's get some practice estimating, subtracting decimals. So, over here it says 12.93 minus 6.1 is approximately equal to what? This squiggly-looking equal sign you can view as roughly equal
to or approximately equal to. So, pause this video and see
if you can figure it out. And, you shouldn't
really need paper for it. The whole point of estimation is to be able to do it quickly
and get close to the answer. You don't have to get the exact answer. Well, let's think about it. The way my brain would do it is 12.93-- Let's just round each of them to the nearest whole number. So, this is going to
be approximately 12.93 if I round to the nearest one or to the nearest whole number, I'm gonna round up to 13. And 6.1, if I round to
the nearest whole number, I'm gonna round down to six. So, I could say this
is roughly 13 minus six which is equal to seven, and that is indeed one
of the choices there. And, when you're doing estimation, you might have gotten a
slightly different result, but I'm guessing that the way that this question was set up, that if you do any type
of reasonable estimate, that you're going to have a number that is closer to seven than
any of the other choices. And to be clear, sometimes you
could do this in your head. For example, 12.93 minus 6.1, you could say 12 minus
six is going to be six. And then you have 93 hundredths minus, you could do this as 10 hundredths. So, it's gonna be 93
hundredths minus 10 hundredths is 83 hundredths, plus .83. So, just like that, you could do something like this and say, alright, the answer here
is gonna be 6.83 exactly. And that, once again, is
approximately equal to seven. But, the whole point of this exercise is to get comfortable estimating things because a lot of times in life you don't need the exact answer. You just need a rough answer, just to know the ball park
of what you're talking about. Let's do another example. So here, we are asked what is 56.75 minus 46.9 approximately equal to? Once again, pause this video
and try to work it out. Well, here I'm gonna do the same thing. I'm just gonna round each
to the nearest whole number and then subtract. And, I'm gonna write it out, but you could do this in your head. So 56.75 rounded to the
nearest whole number is 57 round up, minus 46.9, I would also round up to 47. And, in our head this is
pretty straightforward. This is going to be equal to ten. And, that is indeed is one of the choices. And, normally in life
when you're estimating, you don't have choices like this. I guess this is just the easiest way for-- This if off of the Khan Academy exercises. So, for someone to be able to grade it because estimations can be different, so you have to pick
the one that's at least closest to what you came
up as your estimate. Now, let's do one more example. And, I will write in purple. Alright. So, pause the video again. See if you can figure this out. Alright, so 49.7, I'm
gonna round up to 50, 4.16 I'm gonna round down to four. So, that's going to be
approximately equal to 30-- Oh sorry, that's gonna be
approximately equal to 46. And, we do indeed see
46 as one of the choices right over there. So, hopefully you feel comfortable. There's nothing fancy going on here. The whole point of this
is to just get comfortable doing things like this in
your head and estimating and rounding numbers so you
can get a ball park sense of what this difference is going to be.