Answer
a) 1623, 4 significant figures.
b) 0.000257, 3 significant figures
c) 0.0632, 3 significant figures
d) 3404, 4 significant figures.
Work Step by Step
Since all numbers are in scientific notation, all digits are significant numbers.
To remove the power of ten, putting the number in fixed notation, the decimal must be shifted to the right if the exponent of 10 is positive, or to the left if the exponent is negative, by a number of times equal to the exponent of 10.
a) Exponent: 3, 1.623 shifted 3 times to the right -> 1623, 4 significant figures.
b) Exponent: -4, 2.57 shifted 4 times to the left -> 0.000257, 3 significant figures
c) Exponent: -2, 6.32 shifted 2 times to the left -> 0.0632, 3 significant figures
d) Exponent: 3, 3.404 shifted 3 times to the right -> 3404, 4 significant figures.