Help with this maths sum please..

gabyjane

Ok dd has some maths sums to do and we are struggling..it is multiplication and this is the first one..

69x32

She has been told to work it out using a grid like this:

x 60 9

30

2

Imagine there are lines across and down with that so it is like noughts and crosses and this is how she has been told to work it out

Do the 60x30=1800
then 9x30=270
then 30x2=60 total=2130

Obviously the answer is 2070 so where are we going wrong? i was never any good at doing maths and have never seen it done this way before, dd is adamant she is right so we are at a losing battle.

Help please..

lindsaygalaxy

okay, 69 x 32

30 x 60 = 1800
30 x 9 = 270
2 x 60 = 120
2 x 9 = 18
Total = 2208

The answer should be 2208 not 2070 (just double checked on calculator).

lindsaygalaxy

You need to break both numbers down in the grid. so 69 becomes 60 & 9, and 32 becomes 30 and 2.

Hope this helps.

dieselhead

Sorry I know this isn't helpful but my maths teacher at secondary school tried to persude me to do sums like this and I could never get it to work either! I always do long multiplication like this

69
x32
_____
138
2070
_____
2208

PS I get 2208

lindsaygalaxy

The other way she may have been told (non grid method) is

69
x32
(2 x 9, then 2 x 6)
(write a 0, then 3x2, 3x6)
Total added together

chazbee

dang you beat me to it!

june.elizabeth

60 x 30 = 1800
9 x 30 = 270
60 x 2 = 120
9 x 2 = 18

total = 2208

69 x 32 = 2208

msb5262

There should be 4 x sums to do if you're using the grid method. Tens x tens, tens x units, units x tens, units x units if you see what I mean.
Use this method and we have...
60 x 30 = 1800
60 x 2 = 120
9 x 30 = 270
9 x 2 = 18
1800 + 120 = 1920
270 + 18 = 288
288 + 1920 = 2208 (and this is the correct answer!).
If you don't believe me, try doing 2208 divided by 69 on a calculator.
Hope that helps!
MsB

peachyprice

Is this all part of the 'let's see how complicated we can make maths' system

For simplicity you still can't beat the good old column method.

msb5262

Actually I think the grid method for long multiplication is brilliant - you can't use the column method until you understand how this works. I know it's a bit alien to our generation (I'm 43) but believe me, it works well with children.

PasturesNew

gabyjane wrote: »

Ok dd has some maths sums to do and we are struggling..it is multiplication and this is the first one..

69x32

She has been told to work it out using a grid like this:

x 60 9

30

2

Imagine there are lines across and down with that so it is like noughts and crosses and this is how she has been told to work it out

Do the 60x30=1800
then 9x30=270
then 30x2=60 total=2130

Obviously the answer is 2070 so where are we going wrong? i was never any good at doing maths and have never seen it done this way before, dd is adamant she is right so we are at a losing battle.

Help please..

You're doing it wrong.

69x32
So you want:
60 x 30
9 x 30
60 x 2
9 x 2

And add that lot up... you slipped in a 30x2 which doesn't exist.