Which digits can replace _ to make a true statement? 6,456 <6,_12 <6,788

5, 6, and 7. The number in the hundreds place has to be bigger than the first number's hundreds place because the tens place is bigger in the first number. But it also has to be less then the second number, but because the last number has a tens place digit of more than the second number, you can also put 7.