diff --git a/col.go b/col.go
index 9ba155d..c1d53d6 100644
--- a/col.go
+++ b/col.go
@@ -161,6 +161,10 @@ type NumberCol struct {
 }
 
 func (c *NumberCol) String(wb *WorkBook) []string {
+	if fNo := wb.Xfs[c.Index].formatNo(); fNo != 0 {
+		t := timeFromExcelTime(c.Float, wb.dateMode == 1)
+		return []string{yymmdd.Format(t, wb.Formats[fNo].str)}
+	}
 	return []string{strconv.FormatFloat(c.Float, 'f', -1, 64)}
 }