by using roman numerals 20 is XX 1 is I 19 is IXX (1+20, I+XX)
I.XX.XII or I.XX.MMXII
1 is I. 20 is XX. 120 is CXX.
This math riddle relates to Roman Numerals where 19 is IXX, 1 is I, and 20 is XX. By removing I from IXX, you are left with XX.
20 is Arabic Numerals XX is Roman Numerals.
71 l=50 xx=20 i=1
XX is the number 20 in Roman numerals. xx
XXIV is the number 24 in Roman numerals. X is 10; 10 x 2 = 20 IV = 5-1 = 4 20+4 = 24
Today's way of expressing 1 20 1999 in Roman numerals is I-XX-MCMXCIX.But in the days of the Romans themselves they probably wrote out the number 1999 as MDCCCCLXXXXVIIII which can be simplified to IMM (-1+2000=1999) in the same way as 9 in Roman numerals is VIIII which is then simplified to IX (-1+10=9).
XX is the number 20 in Roman numerals.
DXXI = 521 (D=500, XX=20, I=1)
Due to rules made during the Middle Ages, today we write out 19 in Roman numerals as XIX. But the Romans themselves would have probably wrote out 19 as XVIIII and then simplified it to IXX. In fact the Latin word for 19 is "undeviginti" which literally means one from twenty. Hence: IXX*IXX = -I*IXX + XX*IXX = +I-XX-XX+CCCC = CCCLXI (361) In Hindu-Arabic numerals: -1(-1+20) + 20(-1+20) = +1-20-20+400 = 361