Of course you can always write them exactly as shown in the question since arabic numbers are used in all western languages. If the question is how would you say this telephone number in Spanish:
Siete-siete-seis
Ocho-siete-nueve-siete
The number seven in Spanish is siete
The ordinal number for ten in Spanish is "décimo"
dieciséis.
diecisiete
Cuarenta
cien
cuarenta
Cinco. This is the spanish written word for the number 5.
Writing the number 435 in Spanish is easy. The number 435 in Spanish is cuatrocientos treinta y cinco.
cuatrocientos ocho
ciento seis
ciento ochenta