0 to 15
These you simply have to learn one by one, there's no pattern yet: cero (0), uno (1), dos (2), tres (3), cuatro (4), cinco (5), seis (6), siete (7), ocho (8), nueve (9), diez (10), once (11), doce (12), trece (13), catorce (14), quince (15).
16 to 19
From 16 on, you can already spot a pattern: dieci- + the digit. dieciséis (16), diecisiete (17), dieciocho (18), diecinueve (19).
20 to 29
The same idea continues in the twenties, now with veinti-: veinte (20), veintiuno (21), veintidós (22), veintitrés (23), veinticuatro (24), veinticinco (25), veintiséis (26), veintisiete (27), veintiocho (28), veintinueve (29). Watch the accents in veintidós, veintitrés and veintiséis.
30 to 99
From 30 on it gets pleasantly regular. The tens: treinta (30), cuarenta (40), cincuenta (50), sesenta (60), setenta (70), ochenta (80), noventa (90).
For everything in between, the rule is simply: tens + y + digit. treinta y uno (31), cuarenta y dos (42), cincuenta y siete (57), sesenta y ocho (68), noventa y nueve (99).
100 to 199
Worth a closer look here: exactly 100 is cien. As soon as anything is added, it becomes ciento: ciento uno (101), ciento veinticinco (125), ciento noventa y nueve (199). So: cien for exactly 100, ciento as the building block for 101 to 199.
Hundreds up to 1000
The hundreds: doscientos (200), trescientos (300), cuatrocientos (400), quinientos (500), seiscientos (600), setecientos (700), ochocientos (800), novecientos (900). quinientos, setecientos and novecientos are especially worth memorising – they're not built mechanically from cinco, siete and nueve.
And right at the top is mil (1000). The same building-block principle then gives you numbers like doscientos cuarenta y siete (247), quinientos ochenta y dos (582) or novecientos noventa y nueve (999).
Ordinal numbers: 1st to 10th
For "the first, second, third …" you need these ten words: primero (1st), segundo (2nd), tercero (3rd), cuarto (4th), quinto (5th), sexto (6th), séptimo (7th), octavo (8th), noveno (9th), décimo (10th). For now you're just learning the basic form – details like primer instead of primero come later, in their own grammar lesson.
Examples
- veintitrés
- cuarenta y dos
- ciento veinticinco
- quinientos
- mil