Crochet pattern query

[Nicolapen]

Round 3: 2dc into the next 10st (20st)

Round 4: *dc, 2dc* 10 times (30st)

What am I required to in round 4?

I have already done round 3 and I started with 5dc in a magic ring

[bgs]

Round 4 written out longhand

Make 1dc in first stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

Make 1 dc in next stitch of round 3

Make 2 dc in next stitch of round 3

[Granny Square]

^What she said.

The pattern was written a little tersely (but not incorrectly). 

It could have been written a tiny bit clearer as: "Round 4: *dc, 2dc*; repeat from * to * a total of 10 times (30st)"

Or, perhaps more typically as "Round 4: *dc, 2dc*; repeat from * to * 9 times (30st)".  (so it's saying the same thing--do it once, then repeat another 9 times)