# 1...
in subtraction and addition, you go by the least precise #.
in multiplication and division, you go by the # with the least sig figs.
14.00 L - 12.5 L = 1.5 L
14.00 is precise to 0.01... 12.5 is precise to 0.1 so your answer can only be precise to 0.1... continuing on...
1.5 L + 102.75 L = 104.2 L
again. 1.5 is precise to 0.1 and 102.75 is precise to 0.01 so your answer can only be precise to 0.1. Now you notice that 1.5+102.75 = 104.25 which rounds to 104.2. this is because of the way rounding is done. if the # to be rounded is even, and the next # = 5, you don't round up. If it's odd, you do. 104.25 rounds to 104.2 whereas 104.35 rounds to 104.4 by convention. ok?
#2...
3.20 g x 24.9 = 79.7 g
3.20 has 3 sig figs... 24.9 has 3 sig figs. So your final answer needs to have 3 sig figs.
#3...
120 g has either 2 or 3 sig figs. You can't tell because the zero may or may not be significant. In chemistry class, to indicate the zero is significant, you will need to either draw a line over the 0.. like this Ō. or place a decimal after the zero like this "120."
examples. 120Ō00 has 4 sig figs. the 120Ō are all significant, the 2 rightmost zeros are not. 12Ō000 has 3 sig figs. 1200Ō0 has 5, etc. "12Ō" has 3 sig figs and so does "120."
in this case, the best bet is to assume the 0 is NOT signficant and claim you couldn't tell and you are erring on the side of caution.
in which case...
435 cal / 120 g = 3.6 cal / g
if you want to consider the 0 significant then...
435 cal / 120 g = 3.625 cal / g
which rounds to 3.62 cal / g... again the 2 rounds to 2 and not up to 3.
but I'd go with 3.6 cal / g...
in subtraction and addition, you go by the least precise #.
in multiplication and division, you go by the # with the least sig figs.
14.00 L - 12.5 L = 1.5 L
14.00 is precise to 0.01... 12.5 is precise to 0.1 so your answer can only be precise to 0.1... continuing on...
1.5 L + 102.75 L = 104.2 L
again. 1.5 is precise to 0.1 and 102.75 is precise to 0.01 so your answer can only be precise to 0.1. Now you notice that 1.5+102.75 = 104.25 which rounds to 104.2. this is because of the way rounding is done. if the # to be rounded is even, and the next # = 5, you don't round up. If it's odd, you do. 104.25 rounds to 104.2 whereas 104.35 rounds to 104.4 by convention. ok?
#2...
3.20 g x 24.9 = 79.7 g
3.20 has 3 sig figs... 24.9 has 3 sig figs. So your final answer needs to have 3 sig figs.
#3...
120 g has either 2 or 3 sig figs. You can't tell because the zero may or may not be significant. In chemistry class, to indicate the zero is significant, you will need to either draw a line over the 0.. like this Ō. or place a decimal after the zero like this "120."
examples. 120Ō00 has 4 sig figs. the 120Ō are all significant, the 2 rightmost zeros are not. 12Ō000 has 3 sig figs. 1200Ō0 has 5, etc. "12Ō" has 3 sig figs and so does "120."
in this case, the best bet is to assume the 0 is NOT signficant and claim you couldn't tell and you are erring on the side of caution.
in which case...
435 cal / 120 g = 3.6 cal / g
if you want to consider the 0 significant then...
435 cal / 120 g = 3.625 cal / g
which rounds to 3.62 cal / g... again the 2 rounds to 2 and not up to 3.
but I'd go with 3.6 cal / g...