Update README.md

unit08_blockchain/lab/README.md

@@ -208,25 +208,30 @@ The Sepolia network allows a user to test an Ethereum application, and using fre
 So, let’s write a bit of code that does some simple maths. In the following we will implement sqrt(), sqr(), mul(), sub(), and add(). First, we open up https://remix.ethereum.org/. and enter the following Solidy contract:
 
 ```solidity
-
-// SPDX-License-Identifier: GPL-3.0
-
-pragma solidity >=0.4.22 <0.9.0;
-contract MyMath {
-    function sqrt(uint x) public pure returns (uint y) {
-        y = uint(sqrtHelper(x));
-    }
-
-    // Internal helper function to compute sqrt
-    function sqrtHelper(uint x) internal pure returns (uint z) {
-        z = x;
-        uint y = (z + (x / z)) / 2;
-        while (y < z) {
-            z = y;
-            y = (z + (x / z)) / 2;
-        }
+pragma solidity ^0.8.0;
+contract mymath {function sqrt(uint x) public view returns (uint y) {
+    uint z = (x + 1) / 2;
+    y = x;
+    while (z < y) {
+        y = z;
+        z = (x / z + z) / 2;
     }
 }
+function sqr(uint a) public view returns (uint) {
+    uint c = a * a;
+    return c;
+  }
+function mul(uint a, uint b) public view returns (uint) {
+    uint c = a * b;
+    return c;
+  }
+function sub(uint a, uint b) public view returns (uint) {
+    return a - b;
+  }
+function add(uint a, uint b) public view returns (uint) {
+    uint c = a + b;
+    return c;
+}}
 
  ```