diff --git a/【实践课外】1.顺序结构/7-1 是不是太胖了.c b/【实践课外】1.顺序结构/7-1 是不是太胖了.c
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--- /dev/null
+++ b/【实践课外】1.顺序结构/7-1 是不是太胖了.c	
@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+int main() {
+    int h;
+
+    scanf("%d", &h);
+
+    printf("%.1lf\n", (double)(h - 100) * 0.9 * 2);
+
+    return 0;
+}
diff --git a/【实践课外】1.顺序结构/7-1 是不是太胖了.jpg b/【实践课外】1.顺序结构/7-1 是不是太胖了.jpg
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diff --git a/【实践课外】1.顺序结构/7-2 计算存款利息.c b/【实践课外】1.顺序结构/7-2 计算存款利息.c
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--- /dev/null
+++ b/【实践课外】1.顺序结构/7-2 计算存款利息.c	
@@ -0,0 +1,14 @@
+#include <math.h>
+#include <stdio.h>
+
+int main() {
+    double money, year, rate;
+
+    scanf("%lf%lf%lf", &money, &year, &rate);
+
+    double k = pow(rate + 1, year);
+
+    printf("interest = %.2lf\n", money * k - money);
+
+    return 0;
+}
diff --git a/【实践课外】1.顺序结构/7-2 计算存款利息.jpg b/【实践课外】1.顺序结构/7-2 计算存款利息.jpg
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diff --git a/【实践课外】1.顺序结构/7-3 整数算术运算.c b/【实践课外】1.顺序结构/7-3 整数算术运算.c
new file mode 100644
index 0000000..231dcd6
--- /dev/null
+++ b/【实践课外】1.顺序结构/7-3 整数算术运算.c	
@@ -0,0 +1,15 @@
+#include <stdio.h>
+
+int main() {
+    int a, b;
+
+    scanf("%d%d", &a, &b);
+
+    printf("%d + %d = %d\n", a, b, a + b);
+    printf("%d - %d = %d\n", a, b, a - b);
+    printf("%d * %d = %d\n", a, b, a * b);
+    printf("%d / %d = %d\n", a, b, a / b);
+    printf("%d %% %d = %d\n", a, b, a % b);
+
+    return 0;
+}
diff --git a/【实践课外】1.顺序结构/7-3 整数算术运算.jpg b/【实践课外】1.顺序结构/7-3 整数算术运算.jpg
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diff --git a/【实践课外】1.顺序结构/7-4 21-大鸟转转转实验室.c b/【实践课外】1.顺序结构/7-4 21-大鸟转转转实验室.c
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index 0000000..1178e6c
--- /dev/null
+++ b/【实践课外】1.顺序结构/7-4 21-大鸟转转转实验室.c	
@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+int main() {
+    int n;
+
+    scanf("%d", &n);
+
+    int a = n % 10;
+    int b = n / 10 % 10;
+    int c = n / 100 % 10;
+    int d = n / 1000;
+
+    printf("%d\n", a * 1000 + b * 100 + c * 10 + d);
+
+    return 0;
+}
diff --git a/【实践课外】1.顺序结构/7-4 21-大鸟转转转实验室.jpg b/【实践课外】1.顺序结构/7-4 21-大鸟转转转实验室.jpg
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diff --git a/【实践课外】1.顺序结构/7-5 石头剪刀布.c b/【实践课外】1.顺序结构/7-5 石头剪刀布.c
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index 0000000..7217e0c
--- /dev/null
+++ b/【实践课外】1.顺序结构/7-5 石头剪刀布.c	
@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+int n;
+double p1, p2, p3, q1, q2, q3;
+
+int main() {
+    scanf("%d%lf%lf%lf%lf%lf%lf", &n, &p1, &p2, &p3, &q1, &q2, &q3);
+
+    double win = p1 * q2 + p2 * q3 + p3 * q1;
+
+    printf("%.4lf\n", win * n);
+
+    return 0;
+}
diff --git a/【实践课外】1.顺序结构/7-5 石头剪刀布.png b/【实践课外】1.顺序结构/7-5 石头剪刀布.png
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