← Atlas of Difficulties
S-09
The child doesn't understand place value: can't see the tens in a two-digit number
What the research says
In primary acalculia, the main deficit is the breakdown of the concept of number: impaired awareness of the composition and place-value structure of numbers, as well as of the meaning of arithmetic signs. Patients can count in order but don't understand the place-value principle and can't operate with generalized quantities. Number drops out of the complex decimal number system.
Lalaeva R.I. Dyscalculia in Children, p. 17 (2005)
Without help
- Can't bridge through ten: doesn't understand why 9+3 = 12
- Mistakes in column arithmetic: mixes up ones and tens, writes digits in the wrong place
- Doesn't understand “borrowing a ten” in subtraction — copies things down mechanically