You may need some basic understanding of Korean to get this, but this is just a bad habit I picked up when I first started learning Korean. I hated learning numbers, so I just didn’t focus on them as much as I should have. So saying English numbers mixed in with Korean is what I came up with because I couldn’t recall the Korean numbers off the top of my head quickly. I’m much better at numbers now, but it still slips out quite frequently and Hyo is trying to eradicate the bad habit. I wonder how long it will take?