12.00000 * 0.9893 + 13.00335 * 0.0107
A) 2
B) 3
C) 4
D) 5
E) 6
Just had this on a test and got it wrong. Would love to know why. Thanks.
4 Answers

The rules for significant figures when multiplying are different to the sig figs rules when adding .
In you problem first sort out the two multiplications and fix the significant figures for each result :
12.00000*0.9893 =11.8716. Sig figs allowed = 4 result = 11.87
13.00335 * 0.0107 = 0.1391358 sig figs allowed = 3 Result = 0.139
Add these: 11.87 + 0.139 = 12.009
Rule for sig figs when adding: The answer must have the number of digits after the decimal the same as the least number of digits after the decimal in the numbers being added. 11.87 has 2 digits after the decimal The answer must have 2 digits after the decimal : 12.009 becomes 12.01
Answer = 12.01 This has 4 sig figs in total. Choice C) is correct.
I am sorry that you did not submit your answer which was wrong – you could then have been guided as to where you were wrong .

It is 4. IN the final answer, it has 4 significant figures not 3

the answer would be b) 3. Because the answer is going to always have the least number of significant figures, which in this case is 0.0107. This only has three because the zeros in front of the actual number act as placeholders.

type of sig figs: 5 popular ruls in sig figs: a million. in multiplication and branch, to nicely known the type of important figures, decide for the numeral of least numbers. on your occasion, 0.0107 and nil.09893 has the least quantity in comparison to others. 2. besides and subtraction, you decide on for the least type of decimal places. on your occasion, 0.9893 and nil.0107 has only 4 decimal places.