Possible 16 digit combinations
#1
Brick 
hello everyone!

I have hash & I know almost a first half of source string and second half is 16 random digits:

PHP Code:
MD5("Workgroup.U1."+16digits// (0000 0000 0000 0000 - 9999 9999 9999 9999) 

this is correct command?
Code:
./hashcat64.bin -m 0 -a 3 hash Workgroup.U1.?d?d?d?d?d?d?d?d?d?d?d?d?d?d?d?d 

I'm not a hacker and reading about numbers like 10 quadrillion..oO makes me feel so confused about is it real to calculate or it takes all my lifetime?

Possible 16 digit combinations
10 000 000 000 000 000 (~ 10,000.0t)
#2
That's doable, depending on your hardware. Might take a few weks/months though.
#3
It's a bad attack if you run a Fixed value in the beginning of the "Password". Use -m 20 instead, you will get a speedup of at least 100.