What is the best estimate for the sum of 34.719 plus 51.626?

86.345 is the actual sum. If you were to estimate, maybe try saying "85" or "86.3". I got these number by only adding 34 and 51 and only 34.7 and 51.6. This way your estimate isn't the exact number, but should be close to it.

34.719+51.626 = 86.345

34.7+51.6 = 86.3

34+51=85