mutiplying predeterminer + noun phrase – English Grammar Profiler
‘double, treble, quadruple’ can be multiplying predeterminers. They come before other determiners in a noun phrase. For example, ‘double the national average.’ 
Other multiplying expressions: *In the English Vocabulary Profile, B1 if followed by a comparative structure.
We can’t be sure the following are all predeterminers because they can be verbs too.
1 DOUBLE THE NATIONAL AVERAGE 615 2 DOUBLE THE LEGAL LIMIT 146 3 DOUBLE THE PREVIOUS YEAR 98 4 DOUBLE THE NATIONAL RATE 97
5 DOUBLE THE PREVIOUS RECORD 81
1 QUADRUPLE THE ORIGINAL PRICE 6
3 TREBLE THE PREVIOUS SEASON 5
1 IS QUADRUPLE THE AMOUNT 4
2 IS QUADRUPLE THE NUMBER 4