Pattern help

Hello…here is what the pattern says

Sleeves…Cast on 27 sts. Work in Twisted Garter St for 6 rows. Work in St st. inc 1 st each end every 4 rows 8 times, every 6 rows 5 times…53 sts. Work even until sleeve measures 20" from beg or desired length.

does this mean I knit 4 rows then increase on the 5th or do the increase on the 4th row?

Thank you in advance for your help. :knitting:

It means increase on the 4th rows (8 times) and then on the 6th rows (5 times).