How to knit a flat circle

I copied this from a hat pattern that started with a flat circle. My plan is to use it for the bottom of a felted bag.

Using double-point needles, CO 5 sts.
Divide sts between needles and join to begin working in the round, being careful not to twist.
K 1 round.
Place a marker to mark beginning of round, or wait until there are a few more sts on the needles first so it is easier to manage. If you find 5 stitches too difficult to work, you can cast on 10 sts and start on Round 3. This will form a small hole that can easily be sewn closed later.
Round 2: [M1, k1] around. 10 sts.
Round 3: [K1, m1] around. 20 sts.
Even-Numbered Rounds 4 through 20[22, 24]: K all sts.
Round 5: [K2, m1] around. 30 sts.
Round 7: [K3, m1] around. 40 sts.
Round 9: [K4, m1] around. 50 sts.Round 11: [K5, m1] around. 60 sts.Round 13: [K6, m1] around. 70 sts.Round 15: [K7, m1] around. 80 sts.Round 17: [K8, m1] around. 90 sts.Round 19: [K9, m1] around. 100 sts.
Etc…..