390,676.238095
24
There is no need to simplify this, it is only a sum. 21 + (10/2) - 18 = 8
Unfortunately, I can see no operators between the numbers and so it is impossible to answer the question. Perhaps you could use words like plus, minus, times, divided by, to the power, etc.
260
18 + 3 = 21
plus or minus 21
25 + 16 - 13 - 21 = 7
21
12
21 for sure
The numbers are: 1 plus square root of 21 and 1 minus square root of 21