Criticize constructively
The last thing a student with dyscalculia needs is a teacher that discriminates or criticizes them negatively. The learning disorder makes it difficult for students to understand and retain knowledge of math. So, when they forget a math process, encouraging them would help them remember faster. As a teacher, you can incorporate encouragement methods to help them feel supported and understood. People with this condition will feel comfortable opening up to a teacher that encourages and pushes them to do better.