diff --git a/README.md b/README.md
index b103466139..64ed5aa76b 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ A calculator that calculates simple interest given principal, annual rate of int
 Input:
    p, principal amount
    t, time period in years
-   r, annual rate of interest
+   r, rate of interest per year
 Output
    simple interest = p*t*r
 ```