Sì, ci avevo pensato anch'io...infatti inizialmente utilizzavo solo page="inputnumber.jsp". In quel caso però il risultato è questo:
codice:
org.apache.jasper.JasperException: An exception occurred processing JSP page /welcomeJSF.jsp at line 15

12: <f:view>
13:     <html>
14:         <body>
15:             <jsp:forward page="inputnumber.jsp" />
16:         </body>
17:     </html>
18: </f:view>


Stacktrace:
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:553)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:442)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:408)
	com.sun.faces.application.ViewHandlerImpl.executePageToBuildView(ViewHandlerImpl.java:442)
	com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:115)
	com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
	com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
	com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
	javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

root cause

org.apache.jasper.JasperException: javax.servlet.ServletException: javax.servlet.jsp.JspException: java.lang.IllegalStateException
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:534)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:442)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:745)
	org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:716)
	org.apache.jsp.welcomeJSF_jsp._jspx_meth_f_005fview_005f0(welcomeJSF_jsp.java:106)
	org.apache.jsp.welcomeJSF_jsp._jspService(welcomeJSF_jsp.java:67)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:408)
	com.sun.faces.application.ViewHandlerImpl.executePageToBuildView(ViewHandlerImpl.java:442)
	com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:115)
	com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
	com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
	com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
	javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

root cause

javax.servlet.ServletException: javax.servlet.jsp.JspException: java.lang.IllegalStateException
	org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:907)
	org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:840)
	org.apache.jsp.inputnumber_jsp._jspService(inputnumber_jsp.java:79)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:745)
	org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:716)
	org.apache.jsp.welcomeJSF_jsp._jspx_meth_f_005fview_005f0(welcomeJSF_jsp.java:106)
	org.apache.jsp.welcomeJSF_jsp._jspService(welcomeJSF_jsp.java:67)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:408)
	com.sun.faces.application.ViewHandlerImpl.executePageToBuildView(ViewHandlerImpl.java:442)
	com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:115)
	com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
	com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
	com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
	javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

root cause

java.lang.IllegalStateException
	com.sun.faces.taglib.jsf_core.ViewTag.getComponentType(ViewTag.java:278)
	javax.faces.webapp.UIComponentELTag.createComponent(UIComponentELTag.java:215)
	javax.faces.webapp.UIComponentClassicTagBase.createChild(UIComponentClassicTagBase.java:476)
	javax.faces.webapp.UIComponentClassicTagBase.findComponent(UIComponentClassicTagBase.java:660)
	javax.faces.webapp.UIComponentClassicTagBase.doStartTag(UIComponentClassicTagBase.java:1126)
	com.sun.faces.taglib.jsf_core.ViewTag.doStartTag(ViewTag.java:183)
	org.apache.jsp.inputnumber_jsp._jspx_meth_f_005fview_005f0(inputnumber_jsp.java:96)
	org.apache.jsp.inputnumber_jsp._jspService(inputnumber_jsp.java:71)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:745)
	org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:716)
	org.apache.jsp.welcomeJSF_jsp._jspx_meth_f_005fview_005f0(welcomeJSF_jsp.java:106)
	org.apache.jsp.welcomeJSF_jsp._jspService(welcomeJSF_jsp.java:67)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
	com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:408)
	com.sun.faces.application.ViewHandlerImpl.executePageToBuildView(ViewHandlerImpl.java:442)
	com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:115)
	com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
	com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
	com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
	javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
	org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
...che non so se è meglio o peggio, ma sicuramente non mi basta per capire dov'è l'errore...

Tu ci capisci qualcosa?