public static Number sub(Number a,Number b){
  if (isFloatingPoint(a) || isFloatingPoint(b)) {
    return a.doubleValue() - b.doubleValue();
  }
 else {
    return a.longValue() - b.longValue();
  }
}

public static Number sub ( Number a , Number b ) { if ( isFloatingPoint ( a ) || isFloatingPoint ( b ) ) { return a . doubleValue ( ) - b . doubleValue ( ) ; } else { return a . longValue ( ) - b . longValue ( ) ; } }
returns the value of subtracting the first from the second number .
