How do you solve #612-405#?

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Answer 1 · 2016-07-16T16:43:51

#207#

#612-405 = 207#

Use calculator or write out math

Answer 2 · 2016-07-17T08:59:18

207

There are several ways this type of question can be approached. I am going to show you two methods.

#color(blue)("Method 1 - Splitting the numbers (partitioning)")#
Write #612" as "600+12#
Write #405" as "400+5#

Now write them as:

#" "600+12#
#" "ul(400+5)larr" Subtract"#
#" "200+7#

Answer #207#
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Method 2 - This is the more traditional way")#

#color(brown)("It is the same thing as method 1 but in disguise")#

Write as:

#" "61color(magenta)(2)#
#" "ul(40color(magenta)(5))#

#color(magenta)("Consider the right hand column (units)")#

The 2 is less than 5 so move one of the tens to the units. Then the 1 in 12 becomes 0 and the 2 in 12 becomes #10+2=12# giving

#" "6cancel(1)^0 cancel(2)^(12)#
#" "ul(4color(white)(.)0color(white)(.)5) larr" Subtract"#
#" "2color(white)(.)0color(white)(.)7 #