Kim has a jar of pennies. Use the clues to find out how many pennies are in Kim's jar.
Kim has more than 800 pennies, but less than 900 pennies.
All of the digits in the number of pennies Kim has are even.
The hundreds digit is the sum of the ones and the tens digits.
If you subtract the ones digit from the tens digit, the answer is half the hundreds digit.
How many pennies does Kim have?