What is #7.1-2.1#?

1 Answer
Tony B
Oct 29, 2016

#5.0#

Explanation:

Using column form:

#7.1#
#ul(2.1) larr" Subtract working from right to left"#
#ul(color(white)(2.1)#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dealing with the 1st decimal place we have #1-1=0# so we write:

#7.1#
#ul(2.1) larr" Subtract working from right to left"#
#ul(color(white)(2).0) larr" do not forget the decimal point"#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dealing with the units we have #7-2=5# so we write:

#7.1#
#ul(2.1) #
#ul(5.0) #

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