#color(blue)("The teaching bit")#
A fractions' structure is that of:
#("count")/("size indicator of what is being counted")#
The count and size indicator form a fixed ratio in that
for example:
#1/2=2/4=4/8=32/64# and so on. They all have the same intrinsic value.
To obtain a quarter we need to be able to change the top number into one that is easily divided by 4.
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#color(blue)("Answering your question - using first principle")#
Multiply by 1 and you do not change the value. However, 1 comes in many forms
Note that multiply by #1/4# is the same effect as dividing by #4# so we have:
#[1/4color(red)(xx1)]xx1/4 color(white)("ddd") ->color(white)("ddd") [1/4color(red)(xx1)]-:4#
#color(white)("dddddddddddddd") ->color(white)("ddd") [1/4color(red)(xx4/4)]-:4#
#color(white)("dddddddddddddd") ->color(white)("ddd") [4/16]-:4#
#color(white)("dddddddddddddd") ->color(white)("ddd") [1/16+1/16+1/16+1/16]-:4#
#color(white)("dddddddddddddd") ->color(white)("ddd") 1/16#
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#color(blue)("Answering your question - shortcut method")#
#1/4" of "1/4color(white)("dd") ->color(white)("dd") 1/4xx1/4color(white)("dd")->color(white)("dd")(1xx1)/(4xx4)=1/16#