Mun riga munyi magana a baya game da lambobin roman da kuma ribar sa a yau. Da kyau, kamar yadda kuka sani, batun yana da faɗi sosai kuma dole ne mu girmama wasu ƙa'idodi da dokoki. Ana amfani da lambobin Roman kawai tare da manyan haruffa kuma kowane harafi an bashi a na lamba. Wannan na iya zama ƙa'idar ƙa'ida, amma ba ita kaɗai ba.
Idan zaku yi amfani da Harafin Roman ɗin ku yi ƙoƙari ku yi shi don lambobin surori da kundin aikin; don sunayen fafaroma, sarakuna, da sarakuna, da kuma na majalisa, nadin mukami, taro, da sauransu.
Dokar I : Anan zamu nuna muku daidai dabi'u zuwa kowane harafi
Haruffa: IVXLCDM
Darajoji: 1 5 10 50 100 500 1.000
Misali: XVI = 16; LXVI = 66; DC = 600 MD = 1,500
Dokar II : Idan tsakanin kowane nau'i biyu akwai ƙarami, wannan zai rage darajar sa zuwa na gaba.
Misalai: XIX = (20 - 1) 19; LIV = (55-1) 54; CXXIX = (130 - 1) 129
Dokar III : Ka tuna kar a taba sanya harafi iri daya a jere. A zamanin da "I" ko "X" wasu lokuta ana ganin su har sau huɗu a jere.
Misalai: XIII = 13; XIV = 14; XXXIII = 33; XXXIV = 34
Dokar IV : Domin darajojin da suka fi 4000 girma, Za a sanya layi a kwance sama da alamar, wanda zai nuna cewa za a ninka alamar sau 1000. Misali:
• _
V (5,000)
• _
•X (10,000)
• _
L (50,000)
• _
C (100,000)
• _
D (500,000)
• _
M (1'000,000)
Dokar v : Za a iya yarda Alamu 2 da suka rage a cikin lamba ɗaya matukar dai basa tare (Misali CMIX = 909)