Change ceiling and floor to return NumberInterface. Add fractional part function. Add intValue function. Change StandardPlugin correspondingly.

src/main/java/org/nwapw/abacus/number/NaiveNumber.java

@@ -94,13 +94,23 @@ public class NaiveNumber implements NumberInterface {
     }
 
     @Override
-    public int ceiling() {
-        return (int) Math.ceil(value);
+    public NumberInterface ceiling() {
+        return new NaiveNumber(Math.ceil(value));
     }
 
     @Override
-    public int floor() {
-        return (int) Math.floor(value);
+    public NumberInterface floor() {
+        return new NaiveNumber(Math.floor(value));
+    }
+
+    @Override
+    public NumberInterface fractionalPart() {
+        return new NaiveNumber(value - Math.floor(value));
+    }
+
+    @Override
+    public int intValue() {
+        return (int)value;
     }
 
     @Override

src/main/java/org/nwapw/abacus/number/NumberInterface.java

@@ -83,13 +83,26 @@ public interface NumberInterface {
      * Returns the least integer greater than or equal to the number.
      * @return the least integer >= the number, if int can hold the value.
      */
-    int ceiling();
+    NumberInterface ceiling();
 
     /**
      * Return the greatest integer less than or equal to the number.
      * @return the greatest int >= the number, if int can hold the value.
      */
-    int floor();
+    NumberInterface floor();
+
+    /**
+     * Returns the fractional part of the number.
+     * @return the fractional part of the number.
+     */
+    NumberInterface fractionalPart();
+
+    /**
+     * Returns the integer representation of this number, discarding any fractional part,
+     * if int can hold the value.
+     * @return
+     */
+    int intValue();
 
     /**
      * Promotes this class to another number class.

src/main/java/org/nwapw/abacus/number/PreciseNumber.java

@@ -96,13 +96,38 @@ public class PreciseNumber implements NumberInterface {
     }
 
     @Override
-    public int ceiling() {
-        return (int) Math.ceil(value.doubleValue());
+    public NumberInterface ceiling() {
+        String str = value.toPlainString();
+        int decimalIndex = str.indexOf('.');
+        if(decimalIndex != -1){
+            return this.floor().add(ONE);
+        }
+        return this;
     }
 
     @Override
-    public int floor() {
-        return (int) Math.floor(value.doubleValue());
+    public NumberInterface floor() {
+        String str = value.toPlainString();
+        int decimalIndex = str.indexOf('.');
+        if(decimalIndex != -1){
+            return new PreciseNumber(str.substring(0, decimalIndex));
+        }
+        return this;
+    }
+
+    @Override
+    public NumberInterface fractionalPart() {
+        String str = value.toPlainString();
+        int decimalIndex = str.indexOf('.');
+        if(decimalIndex != -1){
+            return new PreciseNumber(str.substring(decimalIndex + 1));
+        }
+        return ZERO;
+    }
+
+    @Override
+    public int intValue() {
+        return value.intValue();
     }
 
     @Override