diff --git a/Makefile b/Makefile
index 0dbb9eba..8e0ce1ea 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ build:
 	cd src; \
 	yacc -d parse.y; \
 	lex scan.l
-	gcc -o bin/picrin -I./include src/main.c src/state.c src/gc.c src/pair.c src/port.c src/symbol.c src/value.c src/y.tab.c src/lex.yy.c src/bool.c src/vm.c src/init.c
+	gcc -o bin/picrin -I./include src/main.c src/state.c src/gc.c src/pair.c src/port.c src/symbol.c src/value.c src/y.tab.c src/lex.yy.c src/bool.c src/vm.c src/init.c src/number.c
 
 clean:
 	rm -f src/y.tab.c src/y.tab.h src/lex.yy.c
diff --git a/src/init.c b/src/init.c
index 9775b408..ce4defff 100644
--- a/src/init.c
+++ b/src/init.c
@@ -1,6 +1,7 @@
 #include "picrin.h"
 
 void pic_init_port(pic_state *);
+void pic_init_number(pic_state *);
 
 #define DONE pic_gc_arena_restore(pic, ai);
 
@@ -11,4 +12,5 @@ pic_init_core(pic_state *pic)
 
   ai = pic_gc_arena_preserve(pic);
   pic_init_port(pic); DONE;
+  pic_init_number(pic); DONE;
 }
diff --git a/src/number.c b/src/number.c
new file mode 100644
index 00000000..8c591a70
--- /dev/null
+++ b/src/number.c
@@ -0,0 +1,86 @@
+#include <math.h>
+
+#include "picrin.h"
+#include "picrin/value.h"
+
+static pic_value
+pic_number_sqrt(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = sqrt(f);
+  return pic_float_value(f);
+}
+
+static pic_value
+pic_number_sin(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = sin(f);
+  return pic_float_value(f);
+}
+
+static pic_value
+pic_number_cos(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = cos(f);
+  return pic_float_value(f);
+}
+
+static pic_value
+pic_number_tan(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = tan(f);
+  return pic_float_value(f);
+}
+
+static pic_value
+pic_number_acos(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = acos(f);
+  return pic_float_value(f);
+}
+
+static pic_value
+pic_number_asin(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = asin(f);
+  return pic_float_value(f);
+}
+
+static pic_value
+pic_number_atan(pic_state *pic)
+{
+  double f;
+
+  pic_get_args(pic, "f", &f);
+  f = atan(f);
+  return pic_float_value(f);
+}
+
+void
+pic_init_number(pic_state *pic)
+{
+  pic_defun(pic, "sqrt", pic_number_sqrt);
+  pic_defun(pic, "sin", pic_number_sin);
+  pic_defun(pic, "cos", pic_number_cos);
+  pic_defun(pic, "tan", pic_number_tan);
+  pic_defun(pic, "acos", pic_number_acos);
+  pic_defun(pic, "asin", pic_number_asin);
+  pic_defun(pic, "atan", pic_number_atan);
+}