diff --git a/solutions/c/largest-series-product/1/largest_series_product.c b/solutions/c/largest-series-product/1/largest_series_product.c
new file mode 100644
index 0000000..b993faa
--- /dev/null
+++ b/solutions/c/largest-series-product/1/largest_series_product.c
@@ -0,0 +1,25 @@
+#include "largest_series_product.h"
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+int64_t largest_series_product(char *digits, size_t span){
+    if (!digits || span == 0) return -1;
+
+    size_t len = strlen(digits);
+    if (span > len) return -1;
+
+    int64_t max = 0;
+
+    for (size_t i = 0, out_limit = len - span + 1; i < out_limit; i++) {
+        int64_t n = 1;
+        for (size_t j = i, in_limit = i + span; j < len && j < in_limit; j++) {
+            if (digits[j] >= '0' && digits[j] <= '9') n *= digits[j] - '0';
+            else return -1;
+        }
+        if (n > max) max = n;
+    }
+
+    return max;
+}
diff --git a/solutions/c/largest-series-product/1/largest_series_product.h b/solutions/c/largest-series-product/1/largest_series_product.h
new file mode 100644
index 0000000..39a9258
--- /dev/null
+++ b/solutions/c/largest-series-product/1/largest_series_product.h
@@ -0,0 +1,9 @@
+#ifndef LARGEST_SERIES_PRODUCT_H
+#define LARGEST_SERIES_PRODUCT_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+int64_t largest_series_product(char *digits, size_t span);
+
+#endif