The middle value must be between 2.463 and 2.480. This means that the possible choics for the middle value are:
2.464
2.465
2.466
2.467
2.468
2.469
2.470
2.471
2.471
2.472
2.473
2.474
2.475
2.476
2.477
2.478
2.479
The only value in this list that ends with a "1" is 2.471, so the missing digit must be a 7.
