cumulonimbus wrote:

Bunuel wrote:

Baten80 wrote:

I found the answer options are:

a. 10^210

b. 10^180

c. 10^150

d. 10^90

e. 10^6

I answered B.

What is correct?

10^180 - 10^30 =

Which of the following best approximates the value of the expression above?Yes, answer 10^180 is correct. Note that we need

approximate value of the given expression and as 10^(180) is much larger number than 10^(30) then 10^(30) is pretty much negligible in this case: 10^(180)-10^(30)=~10^(180).

Check similar question for practice:

tough-and-tricky-exponents-and-roots-questions-125956-40.html#p1029229Hope it helps.

Hi Bunnel,

Their are two sets of options on this page.

How to decide b/w 10^180 and 10^179.

Hi cumulonimbus

I think 10^180 is closer. Because 1 is very small, 10^x - 1 is closer to 10^x than 10^(x-1).

Let try few examples, you can see the pattern.

10^2 - 1= 99 ==> closer to 10^2 = 100 than 10^1 = 10

10^3 - 1 = 999 ==> closer to 10^3 = 1000 than 10^2 = 100

10^4 - 1 = 9999 ===> closer to 10^4 = 10000 than 10^3 = 1000

.....

10^180 - 1 ==> closer to 10^180 than 10^179

Hope it helps.

_________________

Please +1 KUDO if my post helps. Thank you.

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