If the median is 18 what is the missing digit if the digits are 12 17 21 13 25 and a blank

So you have;

12, 13, 17, _, 21, 25

The mean of 17 and the missing number is 18.

Find out the missing number by multiplying 18 by 2, then subtract it by 17

18 x 2 = 36

36 - 17 = 19

The missing number is 19

Put the numbers in order

12,13,17,21,25, x

(17 + x) / 2 = 18

17 + x = 36

x = 36 - 17

x = 19

lets try it ...

12,13,17,19,21,25 ... now take the 2 middle numbers, add them, then divide by 2 to get the median

(17 + 19) / 2 = 18

36/2 = 18

18 = 18 (correct)

ur missing number is 19 <===