Question

Explain why science is is you significant digits

Answer 1

Why use significant digits you ask? Significant digits or significant figures are use as to not be too precise of an actual calculated measure.
Long decimal numbers location like 3.45 * sqrt of 3 gives 5.975575286112627.
That number is too precise.

Rounding it to 5.98 shows an exact closeness to the precision of the measure.