Concept:Each number is a perfect square of the form 102k1089​. Its square root is 10k33​, allowing direct decimal placement. Explanation:Since 1089​=33, rewrite each term:10.89​=1001089​​=1033​=3.30.1089​=100001089​​=10033​=0.330.001089​=10000001089​​=100033​=0.0330.00001089​=1000000001089​​=1000033​=0.00330.0000001089​=100000000001089​​=10000033​=0.00033Now add them in order:3.3+0.33=3.633.63+0.033=3.6633.663+0.0033=3.66633.6663+0.00033=3.66663Answer:3.66663 (Option C)