diff --git a/content/numerical/GcdConvolution.h b/content/numerical/GcdConvolution.h
new file mode 100644
index 000000000..9c4c94e1b
--- /dev/null
+++ b/content/numerical/GcdConvolution.h
@@ -0,0 +1,26 @@
+/**
+ * Author: Luke Videckis
+ * Date: 2024-02-20
+ * Source: https://github.com/programming-team-code/programming_team_code/blob/main/convolution/gcd_convolution.hpp
+ * Description: Returns $\displaystyle c[k] = \sum_{gcd(i,j)=k} a[i] \cdot b[j]$.
+ * Time: O(n \log n)
+ * Status: unknown
+ */
+#pragma once
+
+const int mod = 998'244'353;
+vector<int> gcd_convolution(const vector<int>& a,
+  const vector<int>& b) {
+  int n = ssize(a);
+  vector<int> c(n);
+  for (int g = n - 1; g >= 1; g--) {
+    int64_t sum_a = 0, sum_b = 0;
+    for (int i = g; i < n; i += g) {
+      sum_a += a[i], sum_b += b[i];
+      if ((c[g] -= c[i]) < 0) c[g] += mod;
+    }
+    sum_a %= mod, sum_b %= mod;
+    c[g] = (c[g] + sum_a * sum_b) % mod;
+  }
+  return c;
+}
diff --git a/content/numerical/LcmConvolution.h b/content/numerical/LcmConvolution.h
new file mode 100644
index 000000000..3f4ede5f3
--- /dev/null
+++ b/content/numerical/LcmConvolution.h
@@ -0,0 +1,26 @@
+/**
+ * Author: Luke Videckis
+ * Date: 2024-02-20
+ * Source: https://github.com/programming-team-code/programming_team_code/blob/main/convolution/lcm_convolution.hpp
+ * Description: Returns $\displaystyle c[k] = \sum_{lcm(i,j)=k} a[i] \cdot b[j]$.
+ * Time: O(n \log n)
+ * Status: unknown
+ */
+#pragma once
+
+const int mod = 998'244'353;
+vector<int> lcm_convolution(const vector<int>& a,
+  const vector<int>& b) {
+  int n = ssize(a);
+  vector<int64_t> sum_a(n), sum_b(n);
+  vector<int> c(n);
+  for (int i = 1; i < n; i++) {
+    for (int j = i; j < n; j += i)
+      sum_a[j] += a[i], sum_b[j] += b[i];
+    sum_a[i] %= mod, sum_b[i] %= mod;
+    c[i] = (c[i] + sum_a[i] * sum_b[i]) % mod;
+    for (int j = i + i; j < n; j += i)
+      if ((c[j] -= c[i]) < 0) c[j] += mod;
+  }
+  return c;
+}
diff --git a/content/numerical/chapter.tex b/content/numerical/chapter.tex
index afefd94cd..1dbc45be1 100644
--- a/content/numerical/chapter.tex
+++ b/content/numerical/chapter.tex
@@ -31,3 +31,5 @@ \section{Fourier transforms}
 	\kactlimport{FastFourierTransformMod.h}
 	\kactlimport{NumberTheoreticTransform.h}
 	\kactlimport{FastSubsetTransform.h}
+    \kactlimport{GcdConvolution.h}
+    \kactlimport{LcmConvolution.h}