1. First find the six numbers with the smallest deviation and put them in B 1:B6, where B 1 is the above formula (your formula is correct) and the formula is an array formula. After input, use Shift+Ctrl+Enter to end, and drop down to B6.

2. Then use the formula = stdev (b1:B6)/average (b1:B6) to calculate the relative standard deviation (the result is the minimum relative standard deviation of 6 in the number 12).

If you want to find the relative standard deviation of the smallest six numbers in 12, replace your formula with the following formula and repeat the above operation.

=index(a$ 1:a$ 12,match(small((a$ 1:a$ 12+row($ 1:$ 12)/ 10^8),row(a 1)),a$ 1:a$ 12+row($ 1:$ 12)/ 10^8，))