Help with these sig figs adding/subtracting problems?

#a)# #4.55 xx 10^(-5) - 3.1 xx 10^(-5) = ???#
#b)# #0.000159 + 4.0074 = ???#

1 Answer
Truong-Son N.
Sep 19, 2015

a)

#4.55xx10^(-5) - 3.1*10^(-5)#

#= (4.55 - 3.1) xx 10^(-5)#

#= 1.45 xx 10^(-5)#

#= color(blue)(1.5xx10^(-5))#

Here, you take the number with the least number of decimal places and match the number of decimal places. It really means you know with decent certainty only to the tens place. You round up simply because the hundredths place is #>=5#.

b)

#0.000159 + 4.0074#

#= 4.007559#

#= color(blue)(4.0076)#

because the least number of decimal places here is #4#. You round up simply because the ten-thousandths place is #>=5#.

Related questions
Impact of this question
61 views around the world
You can reuse this answer
Creative Commons License