simple calculation

smiley98 said:

okay I am making stupid calc mistakes and I am trying to be more efficient with my mental math. How would you solve this problem quickly?

1.39 x 1/182?
Thanks in advance!

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This is how I did, maybe you'll benifit. Learn to approximate with 10%. This problem is essentially 1.39/182. so u know 10% is 18.2. U know 1% is then 1.82. So u know the answer is going to be something less than 1%. If you want a closer answer. Think of 1.39/1.82 as 14/18 or better yet 14/20. which is 70%, so u know it'll be around .0070 to .0075 percent. I haven't taken the MCAt so I don't know how close the answer choices are. I hope this didn't sount too complicated, but as you can see it gave a good approximation. However if it is, with practice, this method will only take around 10 seconds.

smiley98 said:

okay I am making stupid calc mistakes and I am trying to be more efficient with my mental math. How would you solve this problem quickly?

1.39 x 1/182?
Thanks in advance!

Click to expand...

Use scientific notation for quick calculations on the MCAT.

Convert to scientific notation:
1.39=139x10^-2
Approximate 139x10^-2 to 140x10^-2
And 182 to 180

Now you can easily calculate the rest:

Given: 1.39x(1/182)

=(140/180)x10^-2
~0.8x10^-2

i find that for me personally, writing out the whole thing and then solving for the answer is quickest. for example, if you are working on stoichiometry, instead of doing unit conversions one unit at a time, i'll write out all the conversions, plug everything into the appropriate equation, and then start cancelling out variables/values. one downside to this approach is that you spend time on stuff that you could have done in your head-- but i think it's helped me in terms of accuracy. also, it makes it easier to check your answers later if everything is written out.

it's cetainly not something everyone follows, but it's worked for me fairly well.

gluck!