diff --git a/README.md b/README.md
index a9fd37510b7424bb9ab319e154024a69bceef1e2..7460fded73369083380d59258260c28158d79429 100644
--- a/README.md
+++ b/README.md
@@ -251,6 +251,20 @@
   ~~~
     - with using sine table and sine function can derive the appropriate sine value.
 
+### 3. speed vertification review
+- a. mul
+  ~~~
+  Each sample counts as 0.01 seconds.
+  %   cumulative   self              self     total           
+  time   seconds   seconds    calls  ns/call  ns/call  name    
+  29.82      0.34     0.34 10000000    34.00    34.00  fx_s3132_longlong_mul1
+  29.82      0.68     0.34                             main
+  21.93      0.93     0.25 10000000    25.00    25.00  fx_s3132_longlong_mul2
+  18.42      1.14     0.21 10000000    21.00    21.00  fx_s3132_longlong_mul
+  ~~~
+  - It can be seen that the speed is different for each fuction.
+  - fuction that multiplies fa and fb and divides it by 2^32 is fatest.
+  - from the above result, it can be seen that there is a difference in call speed depending on how the shift operation is used.