We counted to 79 in ASL, let's keep going!
To do the sign for 80, make the hand sign for 8, with your index, ring and pinky fingers pointed up, holding your middle finger down with your thumb, and your palm facing away from you.
Then close your fingers together all pointed forward away from you, for zero.
For 81 through 89, just do the sign for 8, and then the sign for the number 1-9.
Here is a helpful video to show how these signs are done.
ASL Numbers 30-100 in Sign Language - My Smart Hands
(from: wikipedia - american sign language)
Italian: ottanta, unottanta, ottantadue, ottantatre, ottantaquattro, ottantacinque, ottantasei, ottantasette, ottantotto, ottantanove
German: achtzig, einundachtzig, zweiundachtzig, dreiundachtzig, vierundachtzig, fünfundachtzig, sechsundachtzig, siebenundachtzig, achtundachtzig, neunundachtzig
Spanish: ochenta, ochenta y uno, ochenta y dos, ochenta y tres, ochenta y cuatro, ochenta y cinco, ochenta y seis, ochenta y siete, ochenta y ocho, ochenta y nueve
French: quatre-vingts, quatre-vingts-un, quatre vingt deux, quatre vingt trois, quatre vingt quatre, quatre vingt cinq, quatre vingt six, quatre vingt sept, quatre vingt huit, quatre vingt neuf