diff --git a/README.md b/README.md
index b1034661..afb80d68 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ Input:
    t, time period in years
    r, annual rate of interest
 Output
-   simple interest = p*t*r
+   simple interest = p * (1 + r / 100) ^ t
 ```
 
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