The more formal way of writing it (one thousand, two hundred and sixteen) is definitely more clear. But if it helps to remember the more colloquial way (twelve hundred): twelve hundred is a 12 followed by 2 zeros, just like one hundred is a 1 followed by 2 zeros.
The more formal way of writing it (one thousand, two hundred and sixteen) is definitely more clear. But if it helps to remember the more colloquial way (twelve hundred): twelve hundred is a 12 followed by 2 zeros, just like one hundred is a 1 followed by 2 zeros.