Place Value...........Why

One day a man asked a boy ‘how old are you?’ ,the boy said ‘ XV years old’. The man didn’t understand then he said ‘draw dots according to your age.’ the boy said ‘ X : llllllllll and V: lllll’, the man said‘ oh 15 ’ so how can I say 57 years old?’, the boy said ‘LVII years old; L: XXXXX , V: lllll, II: ll’.,the man said ‘ thank you ‘
That man thought a lot then he said’ which is easier 57 or LVII ??’ now lets see
57= 50 + 7
LVII =50 + 5 + 1 + 1
And
578=500 +70 +8
CCCCCLXXVIII= 100+100+100+100+100+50+10+10+5+1+1+1
Notice : that system of the boy is the Latin system in that system C= 100 ,L=50,X=10,V=5,and I=1 but in our decimal system the value of 5 is changed according to its place
In 57 è 50 fifty but in 578 è 500 five hundred
The base of our system is 10: so
1 ten = 10 units, 1 hundred = 10 tens and so on.