How can I quickly decipher Roman Numerals to numbers?

Roman numeral

NOUN:

Any of the numerical symbols formed with the Roman letters

I, V, X, L, C, D, and M, representing respectively the numbers

1, 5, 10, 50, 100, 500, and 1000, used by the ancient Romans and still used today in certain formal contexts.

I → 1

V → 5

X → 10

L → 50

C → 100

D → 500

M → 1000

Consider the following examples.

Numbers to the left are subtracted and numbers to the right are added.

I → 1

II → 2

III → 3

IV → 4 [Subtract one from five - the one is to the left].

v → 5

VI → 6 [Add one to five - the one is on the right side].

VII → 7 [Add two to five - the two is on the right side].

VIII → 8 [Add three to five - the three is on the right side].

IX → 9 [Subtract one from ten - the one is to the left].

X → 10

XI → 11 [Add one to ten - the one is on the right side].

XII → 12 [Add two to five - the two is on the right side].

And so on.

Learn what numbers the various letters and their combinations represent, then practice deciphering them.

http://mathforum.org/dr.math/faq/faq.roman.html

this link will help u. If u know programming (in C), then mail me. I'll send u a program-code which'll convert decimal no. to roman numeral & vice-versa.

you cant do it quicly however try google, wikipedia or ask.com