significant digits?10 pts for best answer?

Question

*for add/sub**
if i add 67.17and207.2 how may sig figs should the number have?
**for multiply/divison**
if i times 67.17 by 207.2 how many sig figs should that number have?

Answer 1

addition/subtraction - round the 67.17 to 67.2 in order to add it to 207.2, so the answer has 4 sig figs (round it to line up the digits to the right of the decimal place).
multiplication/division - 4 sig figs times/divided by four sig figs = 4 sig figs.

Answer 2

the 1st number has 2 significant digits and second as 1 so the sum shall have one significant digits.

67.17+ 207.2 = 274.27 but 274.2/3 as you take is significant.
if we meant 2nd number to have 2 significant digits we would have said 207.20 ( kindly note that the 2 values though same may not be significant.- when we say 207.2 we may be approximating 207.21 so both are same
for multiply the number of significant digits is again 1.
based on same analogy

Answer 3

1) 67.17 + 207.2 = 274.37
your answer in sig fig would be 2.7437 * 10²

2) 67.17 * 207.2 = (6.717 * 10^1) * (2.072 * 10²)
= 6.717 * 2.072 * 10^3
= 13.917624 * 10^3
= 1.3917624 * 10^4

CHeers

Answer 4

4 sig. digits
all nonzero numbers are significant

Answer 5

Hi. All the whole numbers in your examples end in 7. That give you a hint?

Answer 6

aaaaaaa what??????