The output from DatePart with all these don't include the leading zero.
dd Day of month, leading zero
ww ISO week, leading zero
WW Simple week, leading zero
MM Month, leading zero
yy Year last two digits, leading zero
YY ISO year last two digits, leading zero
hh Hours, leading zero, 12 hour clock
HH Hours, leading zero, 24 hour clock
mm Minutes, leading zero
ss Seconds, leading zero
Output(DatePart("2006-01-01", "yy"))
--> 06