67 Fibonacci Sequence

The program I wrote gives answers that are one less than the answer, but only when the itteration count is between 100-200. More than that it is correct, and less than it is too, just that range has issues. What are some reasons that this would occur? Below is what I have so far:

package fibonaccisequence;

import java.util.Scanner;

public class FibonacciSequence {

public static void main(String[] args) {
    StringBuilder sb = new StringBuilder();
    int length, itCount;
    double oldNum, newNum, tempNum, numIn;

    Scanner sc = new Scanner(System.in);
    System.out.println("Number of inputs: ");
    int count = sc.nextInt();

    for (int i=0; i<count; i++) {
        sc = new Scanner(System.in);
        System.out.println("Enter number to evaluate: ");
        numIn = sc.nextDouble();
        oldNum = 1;
        newNum = 0;
        itCount = 0;

        while (oldNum <= numIn){
            tempNum = oldNum;
            oldNum += newNum;
            newNum = tempNum;
            itCount++;
            System.out.println("Calculation running...");
        }
        System.out.println("Number completed, saving...");
        sb.append(itCount + " ");

    }
    System.out.println(sb);

}

}

Alrighty then, I'll look into that, thanks for the tip!