 Digit-array integer representation

Store an integer in a nonempty array of numeral digits, with the least significant digit first and a fixed radix $b\ge 2$. Normalized digits satisfy $0\le a_i<b$. High-order zeros do not change the value. Adding digit arrays coefficientwise or multiplying them by discrete convolution gives the correct value before normalization, because these operations add or multiply the corresponding powers of the radix. Exact temporary arithmetic, or a radix and accumulator size chosen to prevent integer overflow, is required.