in both numbers you have ones, tens, hundreds, thousands, ten-thousands, one-hundered-thousands, millions, and ten millions places
so the two digits in the ten millions place are 2 and 5. Any number between these two numbers would have to have a ten millions digit of 2, 3, 4, or 5. 1 would fall below 25,000,000 and 6 would be above 55,000,000 so 2,3,4 and 5 are the only numbers that will work.