So move the colour outside the loop, and change it when teh counter hits your "magic number":
string styleColour = "red";
for (int i = currentpg; i < (RowCount / 10); i++)
{
if (i == magicNumber) styleColour = "green";
LinkButton lnk = new LinkButton();
if (currentpage != 0)
{
if (currentpg == currentpage)
{
lnk.Style.Add("fone-size", "14px");
lnk.Style.Add("color", styleColour);