https://www.understood.org/en/learning-attention-issues/child-learning-disabilities/dyscalculia/understanding-dyscalculia

Dyscalculia is a learning disability in math. Kids with dyscalculia can have trouble with quantities and concepts like bigger and smaller. They may also struggle with math symbols and more complex math. Having dyscalculia doesn’t mean kids aren’t smart. But they may have a hard time applying what they know to solve math problems.