2.56
1.239 rounded to 3 significant digits is 1.24
555
6.33
To round to the nearest hundred and ten both being 200 it leaves 9 possibilities. 195,196,197,198,199,201,202,203, and 204. The only one with digits adding up to 19 is 199.
-12
100 (rounded up to the nearest 200).
199
10 (565,566,567,568,569,570,571,572,573,574)
The number would be 2666. 6 is repeated 3 times. Rounded to the nearest hundred is 2700 and rounded to the nearest thousand is 3000.
686.88 rounded to 3 significant digits is 687
1.239 rounded to 3 significant digits is 1.24
The thousandths place is the third digit after the decimal point. 86.255 only has 3 digits after the decimal point so it is already (possibly) rounded to the nearest thousandth.
555
555
3.12 rounded to the nearest tenth is 3.1. Rounded to the nearest one is 3. Rounded to the nearest ten is 0.
6.33
Just one. The trailing zeros are not significant. * * * * * Not true. Integers with trailing 0s are ambiguous. You cannot differentiate between 500o as a number rounded to the nearest thousand (1 significant digit), or the nearest hundred (2 sig digits), or the nearest ten (3 sig digits) or the nearest unit (4 sig digits).