I noticed when answering this related question that I would never say a bigger number of. I have no issues with 5 is a bigger number than 3 (though I would probably say a larger or greater number instead), but a bigger number of people than expected sounds just plain wrong. I also don't seem to be alone in this:
It was suggested to me in chat that this might be because bigger and number of have different registers and they sound incongruous together. I am not quite convinced of that though, neither seems particularly associated with any specific register.
What is different about that particular construction? Why are a larger/greater number of and a bigger number than fine yet a bigger number of not? Also, am I imagining this? At least one native speaker active on this site seems to disagree, am I alone in my distaste?
Best Answer
I think someone on Mathematics would be able to answer this question best; mathematicians never say bigger number. I cannot put my finger on it either but to say that, colloquially, bigger is a psychical size; larger is a quantity.
What follows is basically a cut and paste from englishforums.com -user Terr3
(I'm not sure how great this can possibly be considering all the grammar and spelling mistakes I cleaned up):