Shouldn't some word meaning plus be used instead? Since 9=/=10 and 1=/=10
Ah, so, mathamiticly, this statement is valid, but Naŭ kaj unu estas dekoj. is wrong
But actually, the grammatically correct forms are
Nine and one are ten Nine plus one is ten
When translating from Esp to English you can type numbers instead of spelling out the numbers. On other questions I have been marked wrong for using digits (1 2 3 4 etc...) for words.
on this question:
9 and 1 is 10 was correct.