diff --git a/MathPad/NSIndexPath+MPAdditions.h b/MathPad/NSIndexPath+MPAdditions.h
index 56b8c8e..185ac20 100644
--- a/MathPad/NSIndexPath+MPAdditions.h
+++ b/MathPad/NSIndexPath+MPAdditions.h
@@ -34,4 +34,8 @@
 - (NSIndexPath *)indexPathByIncrementingLastIndex;
 - (NSIndexPath *)indexPathByDecrementingLastIndex;
 
+- (NSIndexPath *)indexPathWithLength:(NSUInteger)length; // use length indexes from the receiver, exception if too much
+
+- (NSIndexPath *)commonIndexPathWith:(NSIndexPath *)indexPath;
+
 @end
diff --git a/MathPad/NSString+MPExpressionElement.m b/MathPad/NSString+MPExpressionElement.m
index 380108a..9102518 100644
--- a/MathPad/NSString+MPExpressionElement.m
+++ b/MathPad/NSString+MPExpressionElement.m
@@ -7,6 +7,7 @@
 //
 
 #import "NSString+MPExpressionElement.h"
+#import "MPElementParser.h"
 
 @implementation NSString (MPExpressionElement)
 
@@ -20,30 +21,9 @@
     return NO;
 }
 
-- (double)doubleValue
+- (NSDecimalNumber *)evaluate:(MPParseError *__autoreleasing *)error
 {
-#warning Unimplemented Method
-    return 0;
-}
-
-- (float)floatValue
-{
-    return (float)[self doubleValue];
-}
-
-- (int)intValue
-{
-    return (int)[self doubleValue];
-}
-
-- (NSInteger)integerValue
-{
-    return (NSInteger)[self doubleValue];
-}
-
-- (long long)longLongValue
-{
-    return (long long)[self doubleValue];
+    return [[[MPElementParser alloc] init] parseElement:self error:error].standaloneValue;
 }
 
 @end