diff --git a/cap3/work22.go b/cap3/work22.go
index 12b9aa2..e86e349 100644
--- a/cap3/work22.go
+++ b/cap3/work22.go
@@ -1,5 +1,13 @@
 package cap3
 
-func Work22() {
+func Work22(nums []int) int {
+	size := len(nums)
+	maxSum := 0
+	for i := size; i < size*2; i++ {
+		i1, i2, i3, i4 := (i-1)%size, i%size, (i+2)%size, (i+2)%size
+		sum := nums[i1] + nums[i2] + nums[i3] + nums[i4]
+		maxSum = max(maxSum, sum)
+	}
 
+	return maxSum
 }
diff --git a/cap3/work23.go b/cap3/work23.go
index 17e9fed..302a1bd 100644
--- a/cap3/work23.go
+++ b/cap3/work23.go
@@ -1 +1,10 @@
 package cap3
+
+func Work23(n int) []int {
+	digits := make([]int, 0, 16)
+	for ; n > 0; n /= 10 {
+		digits = append(digits, n%10)
+	}
+
+	return digits
+}
diff --git a/cap3/work25.go b/cap3/work25.go
index 17e9fed..fc8497a 100644
--- a/cap3/work25.go
+++ b/cap3/work25.go
@@ -1 +1,33 @@
 package cap3
+
+func Work25(callback func(num1, num2, num3, num4, result int)) {
+	// 类似work24
+	check := func(x int) bool {
+		for ; x != 0; x /= 10 {
+			n := x % 10
+			// 如果有一个数字不是素数，直接false
+			if n != 2 && n != 3 && n != 5 && n != 7 {
+				return false
+			}
+		}
+
+		return true
+	}
+
+	// num1三位数，num2一位数，遍历查找
+	for num1 := 100; num1 <= 9999; num1++ {
+		for num2 := 1; num2 <= 0; num2++ {
+			// 乘出来的结果应该是四位数
+			result := num1 * num2
+			if 1000 <= result && result <= 9999 {
+				// 第二个乘数的两个数字位和中间的两个相乘结果
+				num2Digit1, num2Digit2 := num2%10, num2/10
+				num3, num4 := num2Digit1*num1, num2Digit2*num1
+
+				if check(num1) && check(num2) && check(num3) && check(num4) && check(result) {
+					callback(num1, num2, num3, num4, result)
+				}
+			}
+		}
+	}
+}
diff --git a/cap3/work26.go b/cap3/work26.go
index 17e9fed..49116d7 100644
--- a/cap3/work26.go
+++ b/cap3/work26.go
@@ -1 +1,5 @@
 package cap3
+
+func Work26(m, n int) {
+
+}
diff --git a/cap3/work27.go b/cap3/work27.go
index 17e9fed..9588921 100644
--- a/cap3/work27.go
+++ b/cap3/work27.go
@@ -1 +1,11 @@
 package cap3
+
+var _monthNames = []string{
+	"January", "February", "March", "April",
+	"May", "June", "July", "August", "September",
+	"October", "November", "December",
+}
+
+func Work27(n int) string {
+	return _monthNames[n-1]
+}
diff --git a/cap3/work_test.go b/cap3/work_test.go
index 2eae798..c28fc10 100644
--- a/cap3/work_test.go
+++ b/cap3/work_test.go
@@ -88,3 +88,20 @@ func TestWork16(t *testing.T) {
 
 	println()
 }
+
+func TestWork23(t *testing.T) {
+	digits := Work23(123456)
+	fmt.Printf("%d digits\n", len(digits))
+
+	for i := len(digits) - 1; i >= 0; i-- {
+		print(digits[i])
+	}
+
+	println()
+
+	for _, digit := range digits {
+		print(digit)
+	}
+
+	println()
+}