Answer:
9.4.
Step-by-step explanation:
9^2 = 81 and 10^2 = 100
So the value of the square root of 89 is between 9 and 10.
The gap between the squares is 100-81 = 19 and the gap between 89 and 81 is 8 so an estimate of the square root would be 9 + 8/19 of the gap between 9 and 10.
9 + 8/19 = 8.42.
