198 (number) explained

198 (one hundred [and] ninety-eight) is the natural number following 197 and preceding 199.

In mathematics

• 198 is a companion Pell number. Its corresponding Pell number is 70.^[1]
• 198 is both the average of a twin prime pair (197, 199), and the sum of 2 successive primes (97, 101).^{[2] [3]}

In other fields

198 is also:

• The State Highway Police emergency telephone number in Brazil.^{[4] [5]}
• The number of ridges on a U.S. dollar coin.^[6]

See also

• The year AD 198 or 198 BC

Notes and References

1. Web site: A002203 - OEIS . 2023-06-04 . oeis.org.
2. Web site: A014574 - OEIS . 2023-06-04 . oeis.org.
3. Web site: A000040 - OEIS . 2023-06-04 . oeis.org.
4. Web site: Serviços de Utilidade Pública e de Emergência (SUP) . 2023-06-04 . Agência Nacional de Telecomunicações . pt-br.
5. Web site: Telefones Úteis . 2023-06-04 . Secretaria da Segurança Pública . pt-br.
6. Web site: 2022-08-18 . Why Do Coins Have Ridges? Mental Floss . 2022-08-24 . https://web.archive.org/web/20220818064144/https://www.mentalfloss.com/article/28044/how-many-ridges-are-quarter-and-why-are-they-there-first-place . 2022-08-18 .