Find √1.5625.

Problem restatement
Compute the principal square root of 1.5625.

Concept/Approach
Note that 1.25² = (5/4)² = 25/16 = 1.5625.

Step-by-step calculation
√1.5625 = √(25/16) = 5/4 = 1.25

Common pitfalls
Incorrect decimal squaring; using 1.24 or 1.26 by rough rounding.

Final Answer
1.25