isEven, isOdd, isNegative, isMaxValue, isMinValue, isInfinite, isPositive, isSingleValue.

lib/core/num.dart

Index: lib/core/num.dart
diff --git a/lib/core/num.dart b/lib/core/num.dart
index 6bcee5971d90170fd0da67d686e076b709e385a3..a506adebdd290c88ef9a7aedb2cf27c1a124f3d0 100644
--- a/lib/core/num.dart
+++ b/lib/core/num.dart
@@ -49,11 +49,11 @@ abstract class num implements Comparable {
   /** Relational greater than or equal operator. */
   bool operator >=(num other);
 
-  bool isNaN();
+  bool get isNaN;
 
-  bool isNegative();
+  bool get isNegative;
 
-  bool isInfinite();
+  bool get isInfinite;
 
   /** Returns the absolute value of this [num]. */
   num abs();