The system behind Spanish numbers
Spanish numbers are regular once you know four building blocks: the units and teens you memorize, the tens, the hundreds, and the words cien, mil and millón. Above 30 everything is assembled from these parts, so the drill spends most of its time on the joins.
| Range | How it works |
|---|---|
| 1–15 | uno, dos, tres, cuatro, cinco, seis, siete, ocho, nueve, diez, once, doce, trece, catorce, quince |
| 16–19 | dieciséis, diecisiete, dieciocho, diecinueve (one word) |
| 20–29 | veinte, veintiuno, veintidós, veintitrés, veinticuatro, veinticinco, veintiséis, veintisiete, veintiocho, veintinueve (one word) |
| tens | treinta, cuarenta, cincuenta, sesenta, setenta, ochenta, noventa |
| 31–99 | tens + y + unit: treinta y uno, sesenta y cuatro, noventa y nueve (three words) |
| 100 | cien on its own; ciento before anything else: ciento uno, ciento cincuenta |
| hundreds | doscientos, trescientos, cuatrocientos, quinientos, seiscientos, setecientos, ochocientos, novecientos |
| 1.000+ | mil, dos mil, mil quinientos, diez mil, cien mil |
| 1.000.000 | un millón, dos millones (+ de before a noun: dos millones de personas) |
The joins that cause mistakes
One word or three? 16 to 29 are written as one word (dieciséis, veintiuno). From 31 up, it is three words with y (treinta y uno). The older spellings diez y seis and veinte y uno are still accepted, but the one-word forms are what you will see everywhere.
No y after hundreds. 101 is ciento uno, 205 is doscientos cinco. The y only ever sits between tens and units: doscientos treinta y cinco.
Cien or ciento? Cien is exactly 100 (cien personas, cien mil). As soon as anything smaller follows, it becomes ciento: ciento dos.
The three odd hundreds: quinientos (not cincocientos), setecientos (not sietecientos), novecientos (not nuevecientos).
Mil is never “un mil”. 1.000 is mil, 1.500 is mil quinientos, and the year 2025 is dos mil veinticinco. Millón, on the other hand, does take un.
Gender and shortening
Uno becomes un before a masculine noun and una before a feminine one: un libro, veintiún libros, treinta y una personas. Hundreds agree too: doscientas páginas, quinientas personas. In this drill you type the bare number, so uno and doscientos are the expected forms.
Points and commas
Spain and most of Latin America write thousands with a point and decimals with a comma: 1.500 personas, 2,5 kilos. Mexico and some Central American countries use the English system. This drill uses points for thousands.
Quick answers
How do you say 100 in Spanish?
Cien when it is exactly one hundred: cien euros, cien mil. Ciento when a smaller number follows: ciento uno, ciento cincuenta. There is no y after it: ciento dos, not ciento y dos.
Is it dieciséis or diez y seis?
Dieciséis, as one word with an accent, is the standard modern spelling. Diez y seis is an older form that is still accepted but rarely used. The same goes for veintiuno (veinte y uno).
How do you say 500, 700 and 900 in Spanish?
Quinientos, setecientos and novecientos. These three hundreds are irregular; the rest follow the pattern: doscientos, trescientos, cuatrocientos, seiscientos, ochocientos.
Is it mil or un mil?
Mil. Spanish never says un mil: mil euros, mil quinientos, el año dos mil. Million does take un: un millón.
When do you use y in Spanish numbers?
Only between tens and units, from 31 to 99: treinta y uno, noventa y nueve, ciento cuarenta y dos. Never after hundreds or thousands: ciento uno, mil doscientos.
Do Spanish numbers change for gender?
Only uno and the hundreds. Uno becomes un before a masculine noun and una before a feminine one (veintiún años, treinta y una personas). Hundreds agree: doscientas páginas.