I use www.m-w.com Merriam-Webster dictionary. I don't if you're looking for a dictionary that translate and I don't know what your native language is, but you can check it out to see if it will help. Ok, this is from last September, but I just wanted to comment. The rule is any number below 10 (single digit number) is suppose to be spelled out and anything 10 and over can be put as the actual number. The above example is correct. However, if you use a numeral within a paragragh, then you use numerals for all numbers, including single digit numbers. Here's a good grammar site that might help It has rules for lots of things!