What ,would be the difference between побольше and больше in this context Would the latter still be ok - would the meaning change?
From what i found online, adding the prefix makes it "just a bit more/larger".
"He needs a size bigger" is exactly what you'd hear in shops in the UK. I've reported it as I got it wrong, too.
A size bigger is not the same as a bigger size. It means ONE size bigger, say, from 42 to 43. A bigger size could mean from 42 to 50 or any size above 42.
That's a fair point. I wasn't implying they were synonymous, though, just never thought that "He needs a size bigger" was wrong.
A size does not necessarily mean one size? The phrase a size larger certainly isn't exclusive to a single size.
«Ну́жно» is used with infinitives (ну́жно спать = it's neccessary to sleep) and nouns of the neutral gender (ну́жно яблоко = an apple is neccessary). «Ну́жен» is used with masculine nouns (ну́жен сок = juice is neccessary), and «нужна́» is used with feminine nouns (нужна́ вода = water is neccessary).
You can see the gender of the noun in a dictionary, or guess it by looking at the ending of the Nominative case form (masculine nouns usually end in a consonant or -ь, feminine nouns usually end in -а, -я, sometimes in -ь; neutral nouns end in -о, -е).
So размер is a masculine noun (ends with a consonant), therefore we say: "...нужен размер...".
You can say: "Ему нужно подобрать размер побольше" ("He needs to select a bigger size").
I literally wrote "he needs a larger size," was told it was incorrect, then typed in "he needs a size up" (which sounds grmatically incorrect in English) and was given the alternative "he needs a aize larger" ... what is the difference from my original answer??
The structure of the Russian sentence is different from the English one. Russian is closer to 'To-him is-neccessary size larger'.
I thought that Russian put the adjectives in front of the nouns they modify. How did побольше end up behind its noun?
Adjectives (in fact, most modifiers except её/его/их) are put before the noun if they change their form to match the gender, number and case of that noun. Otherwise, they are put after noun.
«Побольше» 'bigger' is an indeclinable form of adjective. Indeclinable adjectives or forms of adjectives come after nouns.
See my comment here for examples: https://www.duolingo.com/comment/11877095
Russian adjectives also have two vowels at the end.... ой, ий, ый, ое, ие, ая, яя... What did I miss? Anyway, I don't think it is an adjective. :) Adverb?
UPDATE: I was wrong, of course, so thanks for the excellent answer that cleared this up!!