diff --git a/project/euler/digit.go b/project/euler/digit.go
new file mode 100644
index 0000000..8e7cde7
--- /dev/null
+++ b/project/euler/digit.go
@@ -0,0 +1,38 @@
+package euler
+
+// CalculateDigitNumber 桁数を計算する
+func CalculateDigitNumber(n int) int {
+	if n == 0 {
+		return 1
+	}
+	if n < 0 {
+		n *= -1
+	}
+	m := 0
+	for i := 1; n/i > 0; i *= 10 {
+		m++
+	}
+	return m
+}
+
+// CirculateDigit 末尾の桁の數字を先頭に移動する
+func CirculateDigit(n int) int {
+	minus := false
+	if n < 0 {
+		minus = true
+		n *= -1
+	}
+
+	m := 1
+	for n/(10*m) > 0 {
+		m *= 10
+	}
+	h := n / 10
+	t := n % 10
+
+	l := t*m + h
+	if minus {
+		return -1 * l
+	}
+	return l
+}
diff --git a/project/euler/digit_test.go b/project/euler/digit_test.go
new file mode 100644
index 0000000..71289b8
--- /dev/null
+++ b/project/euler/digit_test.go
@@ -0,0 +1,58 @@
+package euler
+
+import "testing"
+
+func TestCalculateDigitNumber(t *testing.T) {
+	cases := []struct {
+		Input    int
+		Expected int
+	}{
+		{-10, 2},
+		{-1, 1},
+		{0, 1},
+		{1, 1},
+		{3, 1},
+		{10, 2},
+		{41, 2},
+		{100, 3},
+		{213, 3},
+	}
+	for _, tc := range cases {
+		if actual := CalculateDigitNumber(tc.Input); actual != tc.Expected {
+			t.Errorf(
+				"Input:%v\nExpected:%v\nActual:%v",
+				tc.Input,
+				tc.Expected,
+				actual,
+			)
+		}
+	}
+}
+
+func TestCirculateDigit(t *testing.T) {
+	cases := []struct {
+		Input    int
+		Expected int
+	}{
+		// 負數
+		{-1, -1}, {-10, -1}, {-12, -21},
+		// 0
+		{0, 0},
+		// 正數
+		{1, 1}, {2, 2},
+		{10, 1}, {12, 21},
+		{100, 10}, {102, 210}, {120, 12}, {123, 312},
+		{1000, 100}, {1002, 2100}, {1020, 102}, {1200, 120},
+		{1023, 3102}, {1203, 3120}, {1230, 123}, {1234, 4123},
+	}
+	for _, tc := range cases {
+		if actual := CirculateDigit(tc.Input); actual != tc.Expected {
+			t.Errorf(
+				"Input:%v\nExpected:%v\nActual:%v",
+				tc.Input,
+				tc.Expected,
+				actual,
+			)
+		}
+	}
+}
diff --git a/project/euler/pe0026-0050.go b/project/euler/pe0026-0050.go
index a4769fb..586822c 100644
--- a/project/euler/pe0026-0050.go
+++ b/project/euler/pe0026-0050.go
@@ -404,3 +404,17 @@ func PE0034() int {
 	}
 	return sum
 }
+
+// PE0035 1,000,000以下の巡回素数の個数を計算
+//
+// https://projecteuler.net/problem=35
+func PE0035(n int) int {
+	// n以下の素数列
+	ps := []int{}
+	pg := NewPrimeGenerator()
+	for p := pg.Next(); p <= n; p = pg.Next() {
+		ps = append(ps, p)
+	}
+
+	return 0
+}
diff --git a/project/euler/pe0026-0050_test.go b/project/euler/pe0026-0050_test.go
index 71bafc1..202a098 100644
--- a/project/euler/pe0026-0050_test.go
+++ b/project/euler/pe0026-0050_test.go
@@ -236,4 +236,26 @@ func TestPE0034(t *testing.T) {
 
 // }}}
 
+// PE0035 {{{
+func TestPE0035(t *testing.T) {
+	cases := []struct {
+		Input    int
+		Expected int
+	}{
+		{1000000, 0},
+	}
+	for _, tc := range cases {
+		if actual := PE0035(tc.Input); actual != tc.Expected {
+			t.Errorf(
+				"Input:%v\nExpected:%v\nActual:%v",
+				tc.Input,
+				tc.Expected,
+				actual,
+			)
+		}
+	}
+}
+
+// }}}
+
 // vim:set foldmethod=marker: