3. among the latest models of calculators by citizen, is the bs-101. The bs-101 has a strong metal body, has a 10-digit calculation ability, rubber keys and runs on battery. Being lightweight this calculator also comers with a wallet style case with makes it easy to be carried around. Calculators are a very important part of office accessories, hence they are often given as gifts at various corporate gatherings, to improve business relations among business partners or customers.