When mathematics is rightly understood it not only possesses the truth but also the best beauty. Unfortunately devoid of mathematics there is nothing that one can do. 

Dyscalculia is a disorder where a person lacks skills for performing arithmetic skills. These children lack the skills to that extent that they are not even able to calculate very simple additions and subtractions or to judge gross differences in sizes. A person not being able to distinguish correctly between the size of a bus and a bicycle may cause harm to himself or others. They also have a poor judgment of left and right direction and thus it is difficult for them to maneuver the road all by themselves. They have problem handling cash money, and thus face financial stress. They are poor at reading time and judging its consequence thus, unable to manage time and all other matters related with it. Because of lack of basic skills required for survival these children perform very badly in academics, work life and life in general. 

These children at times may also have Attention Deficit Hyperactivity Disorder and/or dyslexia. Because this disorder shows its head in early stages of child growth, with awareness it can be caught early and set right for the betterment and safety of the child.

My recommendation to schools and teachers is to help these children overcome their shortcomings so that they can build in these children a strong mathematical understanding of numbers and their relationships. Once teachers understand what their student falls short of, they should be more patient and break down every bit of teaching and learning into tiniest of incremental steps and further learn not to make assumptions that their students know this subject from their past.  

Let us teach our children mathematics; the most beautiful and powerful creation of the human spirit. – Stefan Banach