PHP: generate a number from xyz0000 to xyz9999 -

i trying generate list of numbers (that can use in for/foreach cycle).

any number should 10 digits long , have initial prefix (i.e. 0851)

0851xxxxxx
, go 0851000000

0851999999

range('0851000000','0851999999') 

however array take as 84mb in memory (as reported memory_get_usage(1))

less memory consuming way generate these numbers on fly, while iterate in loop.

for example

for($a = 851000000; $a <= 851999999; $a++) {   $number = '0'.(string)$a;   dosomethingwith($number); }