official Guide for Gmat Verbal Review SC #72--- please Help!

[Jinger]

Could anyone explain to me why is A better than B, please!

72) The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than when the used of DDT was sharply restricted in the early 1970's.

A)extinction; its numbers are now five times greater than.
B)extinction; its numbers are now five times more than.

According the the explanations.
B) The use of more instead of greater inappropriately implies there are now more numbers, rather than more gyrfalcons.

From my understanding: its numbers is five times more = the number of birds is five times more

I am so confused! Thank you in advance!

[Jinger]

It seems like that is the only explanation. Thank you!

[Jinger]

Thanks, I will. That's a lot of questions. I surely won't be running out of questions anymore. Do you have to get 100% accuracy while practice to get 800 on the exam.

[Leonard C]

The rule that I follow, and which has served me well so far, is this:

For non-countable items, use "more"
===> I have more food than you.

For countable items, also use "more"
===> I have more dishes that you.

However, if you are comparing numbers, use "greater than" or "less than":
===> 10 is greater than 5, but less than 20.
===> The number of dogs in the pet shop is greater than 5 (here we are comparing the number of dogs)
===> There are more than 5 dogs in the pet shop (here we are comparing dogs)