13rd or 13th

[Revere_ir]

Is it right 13rd? or 13th?

 

[Trisia]

Interesting question, Revere.

3rd - third
13th - thirteenth (it's not formed in the same way as the others: cardinal numeral + third)
23rd - twenty-third
33rd - thirty-third
[...]

 

[Misled Youth]

13th is right. If you spell it out, it will be thirteenth.

If it is a fraction 1/3, then you say it out as one third.

 

[gringo70]

Ok, this is how it goes:
1st,first; 2nd,second; 3rd,third, 4th,fourth; 5th; 6th;7th; 8th; 9th, 10th;11th; 12th; 13th; 14th; 15th; 16th;17th; 18th; 19th; 20th; then:
21st, twenty first; 22nd, twenty second; 23rd, twenty third, 24, twenty forth; 26th; 27th; 28th; 29th; 30th, then back to:
31st, thirty first, 32nd thirty second, 33rd thirty third, 34 thirty fourth, 35th; 36th; 37th; 38th; 39th; 40th, then back again to:
41st, forty first; 42nd forty second; 43,forty third; 44th, forty forth, 46th; 47th... From here on it goes indefinitely along this pattern.
For example:100th; 101st; 102nd; 103rd; 104th; 1,000,001st; 1,000,002nd..... Sounds difficult at first, but I,m sure you'll catch up with it soon!