Estimating sums of single digit numbers
which of the following represents the most accurate estimation of 4 + 8? is the answer 5, 10, 20 or 25

The sum of 4 and 8 is equal to 12. In this case, we are asked to determine the number that has the most accurate estimation to the addition of the two numbers. In this case, the answer should be 10. Numbers such as 5, 20 and 25 are really far from 12. 

i think it is 487.5. i may be wrong tho. hope this helps!