Find largest square number - without using calculator
This problem must be done without the use of a calculator. I am able to guesstimate my way to a close enough answer but need some help to improve this.
If n is the largest square number such that , find s when
I got (i) easily since its a perfect square,
For (ii) I wrote the number as
Then nearest perfect square close to 10 is 9, so
From there I figured that the number is between and further got to
The problem is that the required answer is and the weight-age is only 1 mark. Using the calculator suggests this is the exactly correct answer.
But since this is a non-calculator use problem, leads me to believe I am missing an obvious/simpler/faster way of getting there. What am I missing?
Thanks again for all your help.