# Help with a mental math question

case math Math problem
Neue Antwort am 21. März 2023
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Hi, I'm struggling with a simple mental math problem

Please could you share how you would go about calculating 80m/9,040 without using a calculator?

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Beste Antwort

Hi there,

The trick is to break down each number into common denominators:

80 / 9,040

=

8 * 10 / 904 * 10

=

8 / 904

=

2 * 4 / 2 * 452

=

4 / 452

=

2 * 2 / 2 * 226

=

2 / 226

Then you have to make the actual division

= 0,0088.

There are lots of websites where you can practice fast maths - check out online.

Hope this helps!
Cristian

War diese Antwort hilfreich?

Hi Joel,

Make sure you're learning all of the techniques for fast math. There are so many resources online!

For 80m/9,040 I would:

Round to 80,000,000/9,000

Cut the zeros to 80000/9

Round 9  to 10 so 80000/10

Recognize that while this # is 8,000, I rounded 10% up on the deonominator so a smaller demonimator would be somewhere between 8,500 and 9,000….I'll go with 8,750

(editiert)

War diese Antwort hilfreich?

Hi there,

I think this is an interesting question that may be relevant for many people. I would be happy to share my thoughts on it:

• First of all, I would advise you to divide both numbers by 80, given that 9,040 is a multiple of 80. This would result in 1m / 113 = 1,000k / 113.
• Next, you should think about how often 113 fits inside 1,000, which is almost 9 times. As such, the result will be very close to 9,000 (i.e., 8,849).
• Still, while this might be a calculation that you are expected to perform mentally, it is absolutely fine to perform most calculations in writing.

If you would like a more detailed discussion on how to address your specific situation, please don't hesitate to contact me directly.

Best,

Hagen

War diese Antwort hilfreich?

Hi there,

what I would do:

1) I would ask to the interviewer if possible to approximate to 80M/9k (you are approximating denominator by 0.5% - should not be an issue)

2) Symplifying zeros: 80M/9k = 80 000 000 / 9 000 = 80 000 / 9

3) Using fractions to further simplify = 80000 / 9 = 1/9 * 8 * 10000 = 0.1111 (you should learn simple fractions “by heart” ½= 0.5 ⅓,= 0.33, ¼ = 0.25, , 1/5, 1/6, 1/7, 1/8, 1/9) * 8 * 10000 = 8888.9

Hope this helps

Feel free to DM for more details

War diese Antwort hilfreich?

80m/9040 = ~90m/9k - 10m/9k = 10k - 1.1k = 8.9 k

War diese Antwort hilfreich?

Hi Joël,

Q: How you would go about calculating 80m/9,040 without using a calculator?

I would do the following:

1. Ask if you can approximate
2. If that’s possible, simplify it as 80m/9k = 80k/9 ~ 9k
3. Bonus: since the denominator is a bit higher, explain the real final number should be slightly lower

If they don’t want you to approximate, you will have to do the actual math as 8M/904. A possible way to do so is what shown by Cristian.

Best,
Francesco

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Cristian gab die beste Antwort
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