Write as #color(brown)((1.638)/(0.35))#
Multiply the given expression by 1 but in the form of #1=1000/1000#
#(1.638)/(0.35)xx1000/1000" " =" " (1.638xx1000)/(0.35xx1000)#
#" "color(brown)(=1638/350)" " #
This looks different to #1.638/0.35# but if you divide them both out you end up with the same answer. So they are 'equivalent'.
'~~~~~~~~~~~~ For reference ~~~~~~~~~~~~
#1xx350=350#
#2xx350=700#
#3xx350=1050#
#4xx350=1400#
#5xx350=1750#
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Calculating the division into 1638")#
5 lots of 350 is too big a number so we chose 4
#color(brown)("So the first number of our division is 4")#
We have 4 + the remainder of #1638-1400=238#
So we write #4 + 238/350#
#color(brown)(=> 4 238/350)" "# which simplifies to #color(brown)(" "4 17/25)#
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This means that
#(1.638 -: 0.35) = 1638-:350 = 4 17/25" "#
As a decimal this is 4.68
