diff --git a/cap3/work14.go b/cap3/work14.go
index 17e9fed..10e8c1a 100644
--- a/cap3/work14.go
+++ b/cap3/work14.go
@@ -1 +1,22 @@
 package cap3
+
+import "math"
+
+func Work14() []int {
+	resultSet := make([]int, 0)
+	for num := 100; num <= 999; num++ {
+		// 开方取整，再平方判，断是否能获得原来的数，来识别是否为完全平方数
+		intSqrt := int(math.Sqrt(float64(num)) + 0.5)
+		if intSqrt*intSqrt != num {
+			continue
+		}
+
+		// num的百位，十位，个位数，其中有相等即可
+		a, b, c := num/100, num%100/10, num%10
+		if a == b || a == c || b == c {
+			resultSet = append(resultSet, num)
+		}
+	}
+
+	return resultSet
+}
diff --git a/cap3/work15.go b/cap3/work15.go
index 17e9fed..4c677b3 100644
--- a/cap3/work15.go
+++ b/cap3/work15.go
@@ -1 +1,33 @@
 package cap3
+
+func Work15() map[string]string {
+	// 甲队成员
+	teamA := []string{"A", "B", "C"}
+
+	// 乙队成员
+	teamB := []string{"X", "Y", "Z"}
+
+	match := map[string]string{}
+
+	// 遍历所有可能的匹配方式
+	for _, b := range teamB {
+		for _, a := range teamA {
+			// A不和X比赛
+			if a == "A" && b == "X" {
+				continue
+			}
+
+			// C不和X或Z比赛
+			if a == "C" && (b == "X" || b == "Z") {
+				continue
+			}
+
+			// 如果没人匹配，当前就作为对手匹配
+			if _, exists := match[b]; !exists {
+				match[a] = b
+			}
+		}
+	}
+
+	return match
+}
diff --git a/cap3/work16.go b/cap3/work16.go
index 17e9fed..1a3cd8c 100644
--- a/cap3/work16.go
+++ b/cap3/work16.go
@@ -1 +1,18 @@
 package cap3
+
+func Work16(n int) []int {
+	result := make([]int, 0)
+	if n%4 == 0 {
+		result = append(result, 7)
+	}
+
+	if n%7 == 0 {
+		result = append(result, 7)
+	}
+
+	if n%9 == 0 {
+		result = append(result, 9)
+	}
+
+	return result
+}
diff --git a/cap3/work17.go b/cap3/work17.go
index 17e9fed..f53aa08 100644
--- a/cap3/work17.go
+++ b/cap3/work17.go
@@ -1 +1,10 @@
 package cap3
+
+func Work17(a, b, c int) int {
+	result := 70*a + 21*b + 15*c
+	for result > 105 {
+		result -= 105
+	}
+
+	return result
+}
diff --git a/cap3/work18.go b/cap3/work18.go
index 17e9fed..db51acb 100644
--- a/cap3/work18.go
+++ b/cap3/work18.go
@@ -1 +1,45 @@
 package cap3
+
+func Work18(callback func(four, five int)) {
+	// 检查两个数是否由9个不同的数字组成
+	checkDigitUnique := func(a, b int) bool {
+		// 创建一个map来跟踪每个数字是否已经出现过
+		mark := map[int]bool{}
+
+		// 检查第一个数的每一位数字
+		for ; a > 0; a /= 10 {
+			// 如果数字已经在map中，直接返回false
+			if _, exists := mark[a%10]; exists {
+				return false
+			} else {
+				// map标记
+				mark[a%10] = true
+			}
+		}
+
+		for ; b > 0; b /= 10 {
+			if _, exists := mark[b%10]; exists {
+				return false
+			} else {
+				mark[b%10] = true
+			}
+		}
+
+		// map中的数字总数为9，返回true
+		return len(mark) == 9
+	}
+
+	// 遍历所有的四位数
+	for four := 1000; four <= 9999; four++ {
+		// 计算当前四位数的两倍
+		five := 2 * four
+
+		// 检查结果是否为五位数
+		if 10000 <= five && five <= 99999 {
+			// 调用checkUnique函数检查数字是否互不相同，条件满足则回调
+			if checkDigitUnique(four, five) {
+				callback(four, five)
+			}
+		}
+	}
+}
diff --git a/cap3/work19.go b/cap3/work19.go
index 17e9fed..266cba0 100644
--- a/cap3/work19.go
+++ b/cap3/work19.go
@@ -1 +1,31 @@
 package cap3
+
+import (
+	"math"
+	"strings"
+)
+
+var (
+	_hexMap = map[byte]int{
+		'0': 0, '1': 1, '2': 2, '3': 3, '4': 4,
+		'5': 5, '6': 6, '7': 7, '8': 8, '9': 9,
+		'A': 10, 'B': 11, 'C': 12, 'D': 13, 'E': 14, 'F': 15,
+	}
+)
+
+func Work19(hexStr string) int {
+	// 将输入字符串转换为大写，以便匹配映射表
+	hexStr = strings.ToUpper(hexStr)
+
+	decValue := 0
+	// 从字符串最右端开始转换每个字符
+	for i := 0; i < len(hexStr); i++ {
+		char := hexStr[len(hexStr)-1-i]
+		// 获取字符对应的十进制值，计算十进制
+		if value, exists := _hexMap[char]; exists {
+			decValue += value * int(math.Pow(16, float64(i)))
+		}
+	}
+
+	return decValue
+}
diff --git a/cap3/work20.go b/cap3/work20.go
index 17e9fed..c76b646 100644
--- a/cap3/work20.go
+++ b/cap3/work20.go
@@ -1 +1,56 @@
 package cap3
+
+func Work20(callback func(x, y, z int)) {
+	// 检查x, y, z是否包含1到9的所有数字各一次，且不包含0
+	checkDigit := func(x, y, z int) bool {
+		appearCnt := make([]int, 10) // 创建一个数组来存储数字0-9的出现次数
+
+		// x的各位数字
+		appearCnt[x/10]++
+		appearCnt[x%10]++
+
+		// y的各位数字
+		appearCnt[y%10]++
+		appearCnt[y/10%10]++
+		appearCnt[y/100]++
+
+		// z的各位数字
+		appearCnt[z%10]++
+		appearCnt[z/10%10]++
+		appearCnt[z/100%10]++
+		appearCnt[z/1000]++
+
+		// 有0，不符合条件
+		if appearCnt[0] != 0 {
+			return false
+		}
+
+		// 检查1-9出现次数
+		for _, cnt := range appearCnt {
+			if cnt != 1 {
+				return false
+			}
+		}
+
+		return true
+	}
+
+	// 双重循环遍历所有可能的x和y组合
+	// x从12开始到98
+	for x := 12; x < 99; x++ {
+		// y从123开始到986
+		for y := 123; y < 987; y++ {
+			// 如果乘积超过9999，停止内层循环（太大了，已经不符合条件了）
+			z := x * y
+			if z > 9999 {
+				break
+			}
+
+			// 检查x, y, z各位数字情况
+			if checkDigit(x, y, z) {
+				// 回调结果
+				callback(x, y, z)
+			}
+		}
+	}
+}
diff --git a/cap3/work21.go b/cap3/work21.go
index 17e9fed..0619898 100644
--- a/cap3/work21.go
+++ b/cap3/work21.go
@@ -1 +1,41 @@
 package cap3
+
+import "math"
+
+func Work21(callback func(num, sqrt int)) {
+	// 检查两个数是否由9个不同的数字组成
+	checkDigitUnique := func(a, b int) bool {
+		// 创建一个map来跟踪每个数字是否已经出现过
+		mark := map[int]bool{}
+
+		// 检查第一个数的每一位数字
+		for ; a > 0; a /= 10 {
+			// 如果数字已经在map中，直接返回false
+			if _, exists := mark[a%10]; exists {
+				return false
+			} else {
+				// map标记
+				mark[a%10] = true
+			}
+		}
+
+		for ; b > 0; b /= 10 {
+			if _, exists := mark[b%10]; exists {
+				return false
+			} else {
+				mark[b%10] = true
+			}
+		}
+
+		// map中的数字总数为9，返回true
+		return len(mark) == 9
+	}
+
+	for num1 := 100000; num1 < 1000000; num1++ {
+		for num2 := 100; num2 < 1000; num2++ {
+			if math.Sqrt(float64(num1)) == float64(num2) && checkDigitUnique(num1, num2) {
+				callback(num1, num2)
+			}
+		}
+	}
+}
diff --git a/cap3/work22.go b/cap3/work22.go
index 17e9fed..12b9aa2 100644
--- a/cap3/work22.go
+++ b/cap3/work22.go
@@ -1 +1,5 @@
 package cap3
+
+func Work22() {
+
+}
diff --git a/cap3/work24.go b/cap3/work24.go
index 17e9fed..690bcbe 100644
--- a/cap3/work24.go
+++ b/cap3/work24.go
@@ -1 +1,29 @@
 package cap3
+
+func Work24(callback func(num1, num2, result int)) {
+	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 {
+				if check(num1) && check(num2) && check(result) {
+					callback(num1, num2, result)
+				}
+			}
+		}
+	}
+
+}
diff --git a/cap3/work_test.go b/cap3/work_test.go
index 41d0535..2eae798 100644
--- a/cap3/work_test.go
+++ b/cap3/work_test.go
@@ -71,3 +71,20 @@ func TestWork11(t *testing.T) {
 	result = Work11(1000)
 	println(result)
 }
+
+func TestWork15(t *testing.T) {
+	match := Work15()
+	for a, b := range match {
+		fmt.Println(a, " vs ", b)
+	}
+}
+
+func TestWork16(t *testing.T) {
+	result := Work16(123)
+	fmt.Print("can be devide by ")
+	for _, num := range result {
+		fmt.Printf("%d, ", num)
+	}
+
+	println()
+}