The paper reports three studies addressing the role of numeral writing for arithmetic performance. About 650 children in the age range 5-7 years participated in the studies. The results demonstrate a positive correlation between number of digits correctly written and number of arithmetic problems solved. The correlations between number of reversed digits (i.e., written backward) and arithmetic performance were also positive, in particular for the youngest children. A study of procedures used to solve the arithmetic problems showed strong correlations between correctly written numbers (two- to four-digit numbers) and the reports of decomposition and immediate retrieval solution procedures. The results support the conclusion that the acquisition of the number-word sequence and numeral writing skills provide the ground for the development of a mental number sequence that allows quantity value solution procedures.