## Thinking Mathematically (6th Edition)

$1990$
RECALL: $M=1000 \\C=100 \\X=10$ Note that when a smaller numeral is written before a bigger numeral, the value of the smaller is subtracted to the value of the bigger numeral. Thus, $MCMXC = 1000+(1000-100)+(100-10) = 1000+900+90=1990$