is Pentagonal - Java java.lang

Java examples for java.lang:Math Function

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Description

is Pentagonal

Demo Code

/**/*ww w.  j a  v a  2s.c o  m*/
 *
 * maer - Solutions to problems of Project Euler
 * Copyright (C) 2011, Sandeep Gupta
 * http://www.sangupta.com/projects/maer
 *
 * The file is licensed under the the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
//package com.java2s;

public class Main {
    public static boolean isPentagonal(int number) {
        double x = 1 + 24 * number;
        x = Math.sqrt(x);
        x += 1;
        x /= 6;

        long y = (long) x;
        x -= y;

        if (x == 0) {
            return true;
        }

        return false;
    }
}

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