Mention the number of significant figures in the following.
(i) ` 2.64 xx 10 ^ ( 24) ` kg
(ii) ` 64800 ` m
(iii) ` 6.320 ` J
(iv) ` 0.00076 m ^ 2 `

Explanation

(i) Three
(ii) Three
(iii) Four
(iv) Two