The usual rules of rounding apply. If the digit in the 4th decimal place is 5 or more, then 1 is added in the 3rd decimal place. The roots are found using your calculator. The first 4 digits of the repeating decimal are clearly visible already.
a) √51 ≈ 7.141428... ≈ 7.141
b) 0.1326_26 ≈ 0.133
c) ∛971 ≈ 9.90238... ≈ 9.902
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<em>Additional comment</em>
The repeating decimal is equivalent to the fraction 1313/9900.
