excel is adding extra numbers in the 16 decimals when summing

i am dealing with excell to check calculation of students and i do all basic calculations and the checks using AND and IF formulas , i discovered many times the logical check of some SUMS were false even it was visible up to 4 decimal points that is correct i wanted to check further so i increased the decimals to 25 and i saw extra numbers are added in the 16decimal digit even if you do the summation with calculator or hand you will not reach this decimal point 16th .... it happens many times with , i hope any one can help , its weired
as you can see in attachment the circled part in check row is the subraction of the two cells above directly and non of the two numbers have a 16decimal number yet the value in sustraction is showing extra number 9 , also its repeated in the other next columns put with number 45 , and the last column in check row showing false is the result check of the previous numbers are they equal or no and it was false , so from this check i discovered something wrong .
if any one has similar issue let me know and is there a solution


excel decimal error.JPG