Here's today's mentalfloss.com "Throwback" Think Thursday Brain Game, from about four years ago:

Cardinal numbers are counting numbers; 1, 2, 3, and so on. Ordinal numbers, on the other hand, represent an order; 1st, 2nd, 3rd, etc. With this in mind, here's today's Brain Game. And a word of caution: if you answer too quickly, you'll probably answer incorrectly! Good luck:

Counting all ordinal numbers from 1st to 100th,
how many of them end with the suffix "th"?

Here is the ANSWER. 

THE ANSWERS:

73 of them.

The unusual total is the result of the extra "th" entries 11th, 12th, and 13th.

4th through 20th = 17
24th through 30th = 7
34th through 40th = 7
44th through 50th = 7
54th through 60th = 7
64th through 70th = 7
74th through 80th = 7
84th through 90th = 7
94th through 100th = 7

Thanks for playing! Tomorrow, it's Free-for-All Friday!