BIDMAS Evaluating Expression Without Calculator

[Svetlana_Vein]

Hi there,

I'm hoping somebody can help me. I have to evaluate the following expression using BIDMAS rules without using a calculator: 1-2/3²

I can get as far as 1-2/9 but the answer is 7/9. I don't understand how to get from 1-2/9 to 7/9 in my head. For instance 2/9 = 0.2 recurring, but 1-0.22222222222 etc doesn't give me 7/9.

Help me! :)

 

[mfb]

I moved your thread to our homework section.

You can express 1 as 9/9, that makes it easier to subtract 2/9.

In general, if you want to add/subtract with fractions, make sure everything has the same denominator.

 

[Svetlana_Vein]

I moved your thread to our homework section.

You can express 1 as 9/9, that makes it easier to subtract 2/9.

In general, if you want to add/subtract with fractions, make sure everything has the same denominator.

That is perfect - thank you so much! I didn't even think of that! :)

 

[Mark44]

Hi there,

I'm hoping somebody can help me. I have to evaluate the following expression using BIDMAS rules without using a calculator: 1-2/3²

I can get as far as 1-2/9 but the answer is 7/9. I don't understand how to get from 1-2/9 to 7/9 in my head. For instance 2/9 = 0.2 recurring, but 1-0.22222222222 etc doesn't give me 7/9.

Sure it does.
1 - 0.222... (recurring infinitely far) = 0.777... (recurring infinitely far) = 7/9