In my day we learnt Roman numerals as part of our schooling, but I don’t think it has been taught in general, for quite a while. While some packs may have normal numbers, the Major Arcana in most packs still have roman numerals. Anyhow I will list them so you can have an idea of the Roman Numerals converted to our English system numbers if you need it.
0 – Zero,
1 – One,
11 – Two,
111 – Three,
1V – Four,
V – Five,
V1 – Six,
V11 – Seven,
V111 – Eight,
IX – Nine,
X – Ten,
X1 – Eleven,
X11 – Twelve,
X111 – Thirteen,
X1V – Fourteen,
XV – Fifteen,
XV1 – Sixteen,
XV11 – Seventeen,
XV111 – Eighteen,
X1X – Nineteen,
XX – Twenty,
XX1 – Twenty-One.
The number of main symbols in the base cards or Minor Arcana, represent the number of the card.
A fact to remember is the number of objects – Swords, Cups, Wands or Pentacles in the Minor Arcana cards will be the same as the number of the card. For example the 4 of Cups above has 4 Cups in the image. The 10 Swords below has 10 swords in the image.