# (0.510)(0.0922)(150+56)/7.222 in sig figs?

much obliged

Relevance

(0.510)(0.0922)(150+56)/7.222 = 1.34125339 .... before rounding

Strictly following the rules means that when 150 + 56 is computed, then the resulting sum will have only two significant digits, which will limit the answer to two significant digits, or 1.3. If in fact the 150 is known to three significant digits, then the answer will have three significant digits, or 1.34.

0;510 has three significant digits, as does 0.0922. 7.222 has four significant digits. The number of significant digits in the answer is the same as the number of significant digits in the least precise factor for multiplication and division. For addition and subtraction the result is rounded to the least precise column. The least precise column is the tens column for 150, and so the sum of 150 and 56 is 200 to two significant digits. This is why the answer is rounded to two significant digits unless there is justification for three significant digits in 150+56.

I would put little to no stock in what Y S is saying once you get past the statement that 56 has two significant digits. This statement, "Zeros don't count as sig figs after the decimal." is simply wrong.

123.000 has six significant digits

0.123000 has 6 significant digits

Zeros after a decimal and after a nonzero digit ARE significant ... they tell how precisely the measurement was made.

0.000123 has three significant digits. Here the zeros are place holders and do not tell precision in the measurement.

• +56 means 2s.f.

if the number is something like 0.001424, then the answer is 0.0014. Zeros don't count as sig figs after the decimal.

When its 0.0104, then the answer is 0.010... because there was a 1 so the next number counts even though its a 0.