Ask Customs Chracter Set

[atom]

Yes, use rules. There are already hybrid rules available for that, just stack them using:

./oclHashcat ... -r rules/hybrid/prepend_d.rule -r rules/hybrid/prepend_d.rule -r rules/hybrid/prepend_d.rule

3 times for 000 - 999
2 times for 00 - 99
1 time for 0-9