The number 34,235,345 written out in word form is thirty-four million, two hundred thirty-five thousand, three hundred forty-five.
Some people might prefer to use the word 'and', as in thirty-four million, two hundred and thirty-five thousand, three hundred and forty-five.
You can break the number down as follows, from right to left:
5 = five
45 = forty-five
345 = three hundred forty-five
5,345 = five thousand, three hundred forty-five
35,345 = thirty-five thousand, three hundred forty-five
235,345 = two hundred thirty-five thousand, three hundred forty-five
4,235,345 = four million, two hundred thirty-five thousand, three hundred forty-five
34,235, 345 = thirty-four million, two hundred thirty-five thousand, three hundred forty-five
This film tells you more about writing numbers in word form: