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## Class 8 (Foundation)

### Course: Class 8 (Foundation) > Unit 3

Lesson 1: Adding and subtracting decimals# Adding & subtracting decimals word problem

In this math lesson, we learn how to manage a bank account balance by adding and subtracting money with decimals. We start with an initial balance, deposit an amount, and then withdraw cash. By performing these calculations, we determine the final account balance. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

- Couldn't you add 875.50 +(-300) and then add that to the account?? Or am I missing something?(154 votes)
- You could but that would enter BODMAS an entirely different area.(4 votes)

- At2:10, why do people use word problems any way?(5 votes)
- Because it usually makes it more realistic and for some people it is easier.(19 votes)

- Well, he would have just simply subtracted 300$ from $5397.58 in his mind as he does for simple calculations. He used 54 seconds extra for the subtracting method. The answer was same from either ways. I really care about time and try not to waste one second of mine.(10 votes)
- Then you can just fast forward, that's what I do, and if I feel I missed something I go back.(5 votes)

- hey guys quandale dingle here my goofy ahh uncle is holding me captive AAAH My friend barnacle jones junior was hit with a rhinoceros horn because he was listening to no maidens(12 votes)
- u quandale dingle here now bich(1 vote)

- my one and only question is ,is this the same thing as organizing decimals?(:(6 votes)
- my calcalator got it wrong(6 votes)
- how does a calcalator get it wrong(1 vote)

- Namita travels 20km50m every day. Out of this she travels 10km200m by bus and the rest by auto. How much distance does she travel by auto?(1 vote)
- Every day, she travels by bus and by auto which means 20km50m is the total distance. You know 10km200m is traveled by bus and the rest by auto which means this is a subtraction word problem.

1. You could do the subtraction in steps.

- First subtract 50m to get to 20km

- Then subtract 9km to get to 11km

- Finally subtract 800m to get to 10km200m

- Add all of the values you have subtracted to find the distance traveled by auto (9km + 800m + 50m = 9km 850m)

OR

2. You could convert the units to km before doing the subtraction.

- Convert the metres to kilometres so that 20km50m = 20.05km and 10km200m = 10.2km.

Therefore:

Distance traveled by auto = 20km50m - 10km200m

Distance traveled by auto = 20.05km - 10.2km

You should find that this gives you an answer of 9.85km which is the same as 9km 850m.

Hope this helps!(5 votes)

- Can you help me I don't understand math. it is confusing. please help me with the question

1232.234 x 43.54 + 3454.76 = ?

Thanks that would be great.(0 votes)- First, we have to do order of operations. We do the multiplication part first, and then add the product to 3454.76. To do large multiplication problems such as this, all we have to do is multiply each digit in one number by the other number, and then add up the products. Let's multiply each digit in 43.54 by 1232.234.

0.04 * 1232.234 = 49.28936

0.5 * 1232.234 = 616.117

3.00 * 1232.234 = 3696.702

40.00 * 1232.234 = 49289.36

Adding up all of these products, we get 53,651.46836. Now to do the second step of the problem, we add this product to 3454.76. To to this, we simply add up all of the place values, and aggregate the result.

0.00006 + 0.00000 = 0.00006

0.0003 + 0.0000 = 0.003

0.008 + 0.000 = 0.008

0.06 + 0.06 = 0.12

0.4 + 0.7 = 1.1

1.0 + 4.0 = 5.0

50 + 50 = 100

600 + 400 = 1000

3000 + 3000 = 6000

50000 + 00000 = 50000

After we add up all of these values together, we get a final answer of 57, 106.2284. Hope this helped!(10 votes)

- 🥶freezing here🥶(2 votes)
- how to convert measurements(0 votes)
- Hi Rachel,

1) Use google to convert for you (in the form of 'number of units in other units' ex. type "15 feet in m")

2) Use Khan Academy to learn unit conversion: https://www.khanacademy.org/math/arithmetic/rates-and-ratios/unit_conversion/v/unit-conversion

3) See the different ratios to convert between units: https://en.wikipedia.org/wiki/Conversion_of_units

I hope this helps =)(4 votes)

## Video transcript

Leo has $4,522.08 in
his bank account. He deposits another
$875.50 and then withdraws $300 in cash. How much is left
in his account? So he's starting
with $4,522.08. Let's write that down. $4,522.08. And then he deposits, or he
adds, another $875.50. So he's going to add $875.50. When you deposit into an
account, you're putting something into the account, or
you're adding to the account. So after he adds that $875.50,
what does he have? We go back to the penny spot,
or we could view that as the hundredths. A penny is one hundredth
of a dollar. Let me switch colors. We have 8 plus 0 is 8. 0 plus 5 is 5. We have the decimal
right there. 2 plus 5 is 7. 2 plus 7 is 9. 5 plus 8 is 13. Put the 3 down here and regroup
the 1, or carry the 1. 1 plus 4 is 5. So after the $875.50 deposit,
he has $5,397.58. Then he withdraws $300 in cash,
or he takes out $300, so we'll have to subtract that. So then he withdraws $300 and
I just added some trailing zeroes after the decimal. $300 is the same thing as
$300.00 and zero cents. And then we subtract. 8 minus 0 is 8. 5 minus 0 is 5. We have our decimal
right there. 7 minus 0 is 7. 9 minus 0 is 9. 3 minus 3 is 0, and then 5
minus nothing here is 5. So he's the left with, in
his account, $5,097.58.