How do you evaluate #7517.4\div 1.34#?

1 Answer
Jan 29, 2017

This is two sort of cheats for manual calculation method

Explanation:

#color(blue)("Step 1 - making the numbers easier to handle")#

I am guessing that the decimals are giving you trouble. This is a way round that.

Note that:
#7517.4# is the same as #75174xx1/10#
#1.34# is the same as #134xx1/10^2#

So we have: #75174/134xx1/10-:1/10^2#

#75174/134xx1/10xx10^2#

#75174/134xx10#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Step 2 - determine the start value for division")#

#10xx134=1340 larr" not big enough"#
#100xx134=13400 larr" correct count of digits but too small"#
#700xx134=93800larr" too big"#
#500xx134=6" something" larr" start with this one"#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Step 3 - applying the division. This is a different format of long division")#

#" "75174larr" numerator value"#
#color(red)(500)xx134 ->ul(67000) larr" subtract"#
#" "8174#
#color(red)(60)xx134" "->ul(8040) larr" subtract"#
#" "134 #
#color(red)(1)xx134" "->ul(134) larr" sibtract"#
#" "0#

so #75174/134 = color(red)(500+60+1) = 561#

But we still need to deal with the adjustment of #xx10#

So #7517.4/1.34=561xx10 = 5610#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check by calculator #-> 7517.4/1.34 = 5610#