Build a strong foundation of knowledge for your children to get them off to a great start with this Year 4 Add Two 4-Digit Numbers - One Exchange Varied Fluency resource. Our fluency questions are differentiated three ways, so that every one of your children have a chance at accessing their learning. And, to help you out with your marking, we have included an answer page with this resource that is easy to use and understand. It's even easy enough to use that you could encourage your children to mark their own work.