5) 349 cm + 1.10 cm + 100 cm = 500 cm (100 has only 1 sig figs, unless there's a visible decimal point or the measurement is defined)
6) 450 meters / 114 seconds = 4.0 m/s
7) 298.01 kilograms + 34.112 kilograms = 332.12 kg
8) 84 m/s x 31.221 s = 2.6 x 10^3
For the second part, basically you convert the question into sig figs and then round it into 3 digits
1) 77.0653 = 7.71 x 10^1
2) 6,300,178.2 = 6.30 x 10^6
3) 0.00023350 = 2.34 x 10^-4
4) 10.2030 = 1.02 x 10^1
5) 2.895 x 10^21 = 2.90 x 10^21
For the third part, there are rules to memorize.
1) 10.020 = 5 sig figs (all non zero numbers count and all zeros between 2 nonzero number count. zeros that fall after a nonzero number and a decimal count)
2) 0.0002050 = 4 sig figs ( zeros that do not come after a nonzero number are not sig figs. they act only as place holders so are not significant)
3) 190 = 2 sig figs (if the measurement is not defined and there is no decimal point present, then all zeros of a number that does not have a decimal point and is not placed between 2 nonzero numbers act merely as a place holder so is not significant)
4) 270 people in the room = 2 sig figs
For the fourth part, basically you just have to do the multiplication. Because you are multiplying the number by the base of 10, all you have to do is move the decimal point. If the exponent of the base ten is positive, you move the decimal point of the number to the right depending on the number of the exponent of 10. If it is negative, you move to the left depending on the exponent of 10.
1) 1.56 x 10^4 = 1560000
2) 5.6 x 10^-2 = 0.056
3) 3.69 x 10^-2 = 0.369
4) 7.369 x 10^5 = 736900
5) 2.59 x 10^5 = 259000
6) 4.59 x 10^-1 = 0.459
7) 1.369 x 10^-2 = 0.01369
8) 6.9 x 10^4 = 69000
9) 2.59 x 10^3 = 2590
10) 2.09 x 10^-3 = 0.00209
I hope I was helpful. Good luck on chemistry