ff.Format(6.1) returns "6.10" 'min 2 dp
ff.Format(6.12) returns "6.12" '2 dp
ff.Format(6.123) returns "6.123"
ff.Format(6.1234) returns "6.1234"
ff.Format(6.12345) returns "6.12345"
ff.Format(6.123456) returns "6.123456" '6 dp
ff.Format(6.1234567) returns "6.123457" 'max 6 dp, last digit rounded (here: up)
ff.Format(6.12345678) returns "6.123457" 'ditto