Respuesta :
For calculations involving 2 significant figures, 1 cal = 4.2 J.
What is rounding off?
Rounding off implies simplifying a number by preserving its value but moving it closer to the next number. It is done for whole numbers as well as decimals at various places of hundreds, tens, tenths, and so on. Numbers are rounded off to maintain important digits. The number of important figures in a result is simply the number of figures that are reliably known.
Estimation is a sort of rounding-off. Estimation is employed in daily life as well as in areas such as mathematics and physics. Many physical values, such as money, distance traveled, length measured, and so on, are approximated by rounding off the actual number to the next whole number.
Therefore, by rounding off, 1 cal = 4.2 J.
Read more about rounding off, here
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