diff --git a/core/math.rbs b/core/math.rbs
new file mode 100644
index 0000000..a652fa1
--- /dev/null
+++ b/core/math.rbs
@@ -0,0 +1,53 @@
+module Math
+  type double = Integer | Float
+
+  E: Float
+
+  PI: Float
+
+  def self.acos: (double x) -> Float
+
+  def self.acosh: (double x) -> Float
+
+  def self.asin: (double x) -> Float
+
+  def self.asinh: (double x) -> Float
+
+  def self.atan: (double x) -> Float
+
+  def self.atan2: (double y, double x) -> Float
+
+  def self.atanh: (double x) -> Float
+
+  def self.cbrt: (double x) -> Float
+
+  def self.cos: (double x) -> Float
+
+  def self.cosh: (double x) -> Float
+
+  def self.erf: (double x) -> Float
+
+  def self.erfc: (double x) -> Float
+
+  def self.exp: (double x) -> Float
+
+  def self.hypot: (double x, double y) -> Float
+
+  def self.ldexp: (double x, double exp) -> Float
+
+  def self.log: (double x) -> Float
+
+  def self.log10: (double x) -> Float
+
+  def self.log2: (double x) -> Float
+
+  def self.sin: (double x) -> Float
+
+  def self.sinh: (double x) -> Float
+
+  def self.sqrt: (double x) -> Float
+
+  def self.tan: (double x) -> Float
+
+  def self.tanh: (double x) -> Float
+end
diff --git a/test/math.rb b/test/math.rb
new file mode 100644
index 0000000..dd5c45f
--- /dev/null
+++ b/test/math.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+# rubocop:disable Lint/Void
+
+Math::E
+
+Math::PI
+
+Math.acos 0
+Math.acos 0.0
+
+Math.acosh 1
+Math.acosh 1.0
+
+Math.asin 0
+Math.asin 0.0
+
+Math.asinh 0
+Math.asinh 0.0
+
+Math.atan 0
+Math.atan 0.0
+
+Math.atan2 0, 1
+Math.atan2 0.0, 1.0
+
+Math.atanh 0
+Math.atanh 0.0
+
+Math.cbrt 0
+Math.cbrt 0.0
+
+Math.cos 0
+Math.cos 0.0
+
+Math.cosh 0
+Math.cosh 0.0
+
+Math.erf 0
+Math.erf 0.0
+
+Math.erfc 0
+Math.erfc 0.0
+
+Math.exp 0
+Math.exp 0.0
+
+Math.hypot 1, 1
+Math.hypot 1.0, 1.0
+
+Math.ldexp 0, 0
+Math.ldexp 0.0, 0.0
+
+Math.log 1
+Math.log 1.0
+
+Math.log10 1
+Math.log10 1.0
+
+Math.log2 1
+Math.log2 1.0
+
+Math.sin 0
+Math.sin 0.0
+
+Math.sinh 0
+Math.sinh 0.0
+
+Math.sqrt 0
+Math.sqrt 0.0
+
+Math.tan 0
+Math.tan 0.0
+
+Math.tanh 0
+Math.tanh 0.0
+
+# rubocop:enable all