How they counted
Roman numerals
Romans wrote numbers with letters. I is one. V is five. X is ten. You still see these on clocks and on old buildings.
I
1
V
5
X
10
L
50
C
100
D
500
M
1,000
Put letters together
IV
means 4
One before five
IX
means 9
One before ten
XII
means 12
Ten, then two
XL
means 40
Ten before fifty