Code:
{{{{{|safesubst:}}}#ifexpr: 0 <= ({{{1}}}) and ({{{1}}}) < 10|00|{{{{{|safesubst:}}}#ifexpr: 10 <= ({{{1}}}) and ({{{1}}}) < 100|0}}}}{{{{{|safesubst:}}}#expr:{{{1}}}}}

Provides leading zeros to obtain three digits:

  • {{lz3|-1}} gives -1
  • {{lz3|.0}} gives 000
  • {{lz3|.1}} gives 000.1
  • {{lz3|1}} gives 001
  • {{lz3|12}} gives 012
  • {{lz3|123}} gives 123
  • {{lz3|7+5}} gives 012