Thread: compact methods

hello

could anyone help me with my son maths homework
it is subtraction using a compact method
it has all changed since i was at school
is there anyone who knows what this is
i was thinking it maybe this
example=78-34=44
70-30=40 8-4=4 40+4=44
is this right
please help

Originally Posted by misshunnybea

hello

could anyone help me with my son maths homework
it is subtraction using a compact method
it has all changed since i was at school
is there anyone who knows what this is
i was thinking it maybe this
example=78-34=44
70-30=40 8-4=4 40+4=44
is this right
please help

I don't know the method, but if what you write is correct it still makes no mathematical sense.

Now:

78-34=(70-30)+(8-4)=40+4=44

Does make sense. But more interesting is

74-38=(70-30)+(4-8)=40+(4-8)=30+(10+4-8)=36

or:

74-38=(60-30)+(14-8)=30+6=36

RonL

thank you captain black
i have told my son he must ask his teacher to explain this compact method and i will update incase anyone has this problem with there childrens homework.
do not know why they have to change the way they do maths in schools now much easier when i was at school