The square root of 64 can be obtained by the method of repeated subtraction as follows:

(i) 64-1=63 (ii) 63-3=60 (iii) 60-5=55 (iv) 55-7=48 (v) 48-9=39 (vi) 39-11=28 (vii) 28-13=15

(viii) 15-15=0.

We have subtracted successive odd numbers starting from 1 to 64 and obtained 0 at 8^th step.

Therefore, $\sqrt{64}=8$.