BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

700+ approximation

Expert replies
Source: — Problem Solving |

by papgust » Wed Dec 09, 2009 7:34 am
Operator sign is not clear to me. I assume it is "-" for both operators.

If it is a "-" sign, then

10^8 - 10^2 / 10^7 - 10^3

10^(8-2) / 10^(7-3)

10^6 / 10^4

10^(6-4)

10^2
Join the discussion

by Ian Stewart » Wed Dec 09, 2009 9:48 am
papgust, I think you're using a rule we use when dividing, not when subtracting :)

Notice here that 10^8 is 100 million, while 10^2 is just one hundred; 10^8 is one million times larger than 10^2. So 10^8 - 10^2 is only a tiny amount less than 10^8. Similarly 10^7 absolutely dwarfs 10^3 in size; 10^7 - 10^3 is only very slightly less than 10^7. So (10^8 - 10^2)/(10^7 - 10^3) is very close in value to 10^8/10^7 = 10.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Join the discussion

by papgust » Wed Dec 09, 2009 9:01 pm
Oops..!! That is a very bad mistake. Must have been very sleepy while doing it.
Join the discussion