You can use estimation to ensure that your solution is in the right range for many operations.
For example, if you are multiplying 5.4 by 2.8 your answer should be close to the product of the two nearest whole numbers (5 x 3 = 15). Multiplying 5.4 x 2.8 should result in the correct answer, 15.12, which is close to 15. If you ended up with 1.512 you would know that the decimal point is likely in the wrong place.
Similar logic could be used for division (15.12 / 5.4 = 2.8, not 0.28 since 15 / 5 = 3).
