diff --git a/2kyu/evaluate-mathematical-expression/solution.ts b/2kyu/evaluate-mathematical-expression/solution.ts
index 619a3f2..b5fa661 100644
--- a/2kyu/evaluate-mathematical-expression/solution.ts
+++ b/2kyu/evaluate-mathematical-expression/solution.ts
@@ -197,7 +197,7 @@ function parseNumbers(tokens: (Token | ASTNode)[]): (Token | ASTNode)[] {
         nextNextToken as NumberToken
       ]);
       tokens.splice(i, 3, numberNode);
-      i += 3;
+      i += 2;
       continue;
     } else {
       // it is a regular number
@@ -247,6 +247,11 @@ function parseGroups(tokens: (Token | ASTNode)[]): (Token | ASTNode)[] {
   for (const [start, end] of parenthesisPairs) {
     const groupNode = GroupNode.fromTokens(tokens.slice(start + 1, end));
     tokens.splice(start, end - start + 1, groupNode);
+    // update pairs after splice
+    for (let i = 0; i < parenthesisPairs.length; i++) {
+      const [start2, end2] = parenthesisPairs[i];
+      parenthesisPairs[i] = [start2 - (end - start), end2 - (end - start)];
+    }
   }
 
   return tokens;
@@ -293,6 +298,7 @@ function parseMultDiv(tokens: (Token | ASTNode)[]): (Token | ASTNode)[] {
       const operator = token.value as OperatorChars;
       const operatorNode = new OperatorNode(operator, left, right);
       tokens.splice(i - 1, 3, operatorNode);
+      continue;
     }
     i++;
   }
@@ -316,6 +322,7 @@ function parseAddSub(tokens: (Token | ASTNode)[]): (Token | ASTNode)[] {
       const operator = token.value as OperatorChars;
       const operatorNode = new OperatorNode(operator, left, right);
       tokens.splice(i - 1, 3, operatorNode);
+      continue;
     }
     i++;
   }
diff --git a/2kyu/evaluate-mathematical-expression/tests.ts b/2kyu/evaluate-mathematical-expression/tests.ts
index bc7d664..14e9163 100644
--- a/2kyu/evaluate-mathematical-expression/tests.ts
+++ b/2kyu/evaluate-mathematical-expression/tests.ts
@@ -11,6 +11,9 @@ var tests: [string, number][] = [
   ['2 /2+3 * 4.75- -6', 21.25],
   ['12* 123', 1476],
   ['2 / (2 + 3) * 4.33 - -6', 7.732],
+  ['(2 + (2 + 2) / 4) * 3', 9],
+  ['(1 - 2) + -(-(-(-4)))', 3],
+  ['((2.33 / (2.9+3.5)*4) - -6)', 7.45625]
 ];
 
 describe("calc", function () {