Getting line number while using AWK

Using AWK, while I am reading the file, I am separating fields based on the ':' & using NF. I also would like to mention line numbers from the file they are originally from.
How would I take out the line number for them?

I am trying something like following ,

awk -F":" '{
j=1
for (i=1; i<= NF; i++)
{
printf("\t%s\t%s\t%s\n",$j,$i,$(i+1))
}
j=j+1
}' filename

Can anyone please rectify?

Just like NF is the number of the field in the line, NR is "record number" of the record (which, in this case, is the line).

awk -F":" '{
printf("\t%s\n",NR)
for (i=1; i<= NF; i++)
{
printf("\t%s\t%s\n",$i,$(i+1))
}
}' filename

I am not too sure about the syntax, but NR works for sure!

Cheers!