src/HOL/Num.thy
changeset 70226 accbd801fefa
parent 69605 a96320074298
child 70270 4065e3b0e5bf
--- a/src/HOL/Num.thy	Wed May 01 10:40:40 2019 +0000
+++ b/src/HOL/Num.thy	Wed May 01 10:40:42 2019 +0000
@@ -229,6 +229,10 @@
 lemma sqr_conv_mult: "sqr x = x * x"
   by (simp add: num_eq_iff nat_of_num_sqr nat_of_num_mult)
 
+lemma num_double [simp]:
+  "num.Bit0 num.One * n = num.Bit0 n"
+  by (simp add: num_eq_iff nat_of_num_mult)
+
 
 subsection \<open>Binary numerals\<close>