Specific difficulties have been described in a number of areas of mathematics, but difficulty in arithmetic has received the most attention. This may be because all children are required to do arithmetical calculations in the early years of school, but can choose alternative subjects later, and it probably also reflects the fact that arithmetical calculations play an important part in everyday life. Another reason may be that arithmetical difficulty following brain damage in adulthood (dyscalculia) is a well-recognized and well-studied entity. This chapter will focus on specific arithmetic difficulty in children, that is, unexplained, significant delay in arithmetic ability. Although specific arithmetic difficulty was once considered rare, there is now evidence that it is not as uncommon as was previously thought. The psychologist may obtain sufficient information about the child’s arithmetical ability from the Arithmetic section (sub-test) of the Wechsler Intelligence Scale for Children (WISC-IV). This is a commonly used intelligence test that can be used for children from 6 years to 16 years 11 months. This test does not require the child to write down the answers. The problems are timed and they relate to various arithmetical skills. Addition, subtraction, multiplication, and division can all be tested. Some problems also require memorized number facts and subtle operations, such as seeing relevant relationships at a glance. The emphasis of the test is not on mathematical knowledge as such, but on mental computations and concentration. The WISC-IV will also give the psychologist information about other abilities, which may shed light on the child’s difficulties. In the Digit Span sub-test, the child’s ability to remember numbers for a short period is tested. In the Comprehension sub-test, verbal reasoning is involved. If, for example, a child has high comprehension but low arithmetic scores, this may suggest that reasoning ability is adequate in social situations, but not in situations involving numbers. If the psychologist wants further information on arithmetic ability, there are a number of tests that specifically test mathematical skills and allow these to be compared with those of other children of the same age.
