Is the word quarenta the same in Brazilian and European Portuguese?

Yes

The spelling and meaning of "quarenta" are identical in both Brazilian and Continental Portuguese, as it refers strictly to the number 40. The only difference is in pronunciation. In Brazilian Portuguese, the vowels are generally more open and the syllables are more clearly articulated. In Continental Portuguese, unstressed vowels (such as the "e" in the middle of the word) are often reduced or nearly silenced, making the pronunciation sound more "compressed" or "closed."

Brazilian Portuguese examples:

1. Eu tenho quarenta anos. (I am forty years old.)
2. O ônibus chega em quarenta minutos. (The bus arrives in forty minutes.)
3. Ele gastou quarenta reais. (He spent forty reais.)
4. Há quarenta pessoas na festa. (There are forty people at the party.)
5. A caneta custa quarenta centavos. (The pen costs forty cents.)

Continental Portuguese examples:

1. Eu tenho quarenta anos. (I am forty years old.)
2. O autocarro chega em quarenta minutos. (The bus arrives in forty minutes.)
3. Ele gastou quarenta euros. (He spent forty euros.)
4. Há quarenta pessoas na festa. (There are forty people at the party.)
5. A caneta custa quarenta cêntimos. (The pen costs forty cents.)