int maxBitLenOfX = x.getLength() * BigUnsigned::N;
int minBitsPerDigit = bitLen(base) - 1;
int maxDigitLenOfX = ceilingDiv(maxBitLenOfX, minBitsPerDigit);
int maxBitLenOfX = x.getLength() * BigUnsigned::N;
int minBitsPerDigit = bitLen(base) - 1;
int maxDigitLenOfX = ceilingDiv(maxBitLenOfX, minBitsPerDigit);