# Thread: 1972.8 in 2 Sig Figs?

1. ## 1972.8 in 2 Sig Figs?

How do I make 1972.8 into two significant digits? You would have to go up to the next thousand (since it's above 1950), but you get up to 2000 as the next highest number, but that only has one sig fig. Thanks!

2. Originally Posted by mathhelpnow
How do I make 1972.8 into two significant digits? You would have to go up to the next thousand (since it's above 1950), but you get up to 2000 as the next highest number, but that only has one sig fig. Thanks!
$1.9728 \times 10^3 \approx 2.0 \times 10^{3}$ (zeros that follow a decimal point are always significant).

3. One way is shown above. If you want to write the number without a decimal point, then here is what Wikipedia has to say.
The significance of trailing zeros in a number not containing a decimal point can be ambiguous. For example, it may not always be clear if a number like 1300 is accurate to the nearest unit (and just happens coincidentally to be an exact multiple of a hundred) or if it is only shown to the nearest hundred due to rounding or uncertainty... These conventions are not universally used, and it is often necessary to determine from context whether such trailing zeros are intended to be significant. If all else fails, the level of rounding can be specified explicitly. The abbreviation s.f. is sometimes used, for example "20 000 to 2 s.f." or "20 000 (2 sf)".
So, here it would be 2000 to 2 s.f.

4. Originally Posted by mathhelpnow
How do I make 1972.8 into two significant digits? You would have to go up to the next thousand (since it's above 1950), but you get up to 2000 as the next highest number, but that only has one sig fig. Thanks!
You do not need to care too much about the rounded off part, i.e. 2000. 2000 has 4 significant figures, but that does not answer the question. The question only tells you to round off 1972.8 into 2 sig.fig.,which is 2000.

5. Originally Posted by PythagorasNeophyte
You do not need to care too much about the rounded off part, i.e. 2000. 2000 has 4 significant figures, but that does not answer the question. The question only tells you to round off 1972.8 into 2 sig.fig.,which is 2000.
Sorry, but nothing of what you've said is correct. Correct answers have been previously posted.

6. There is another way. 2000 to 2 sig figs can be written as $2 \overline{0} 00$ However Mr. Fantastic's method is the normal way.

-Dan