Transcript here. - Holy Rosary Website

Oh no! I can’t do long
multiplication. What
am I going to do?
Don’t panic!
Take it step by step
and follow this
example.
23 x 14
When multiplying these two numbers
together, it is easier to put
them into a grid.
23 x 14
20
10
4
The first thing to do is
partition the numbers into
tens and units.
3
23 x 14
Multiply the number above
the box with that on the left,
writing the answer inside the box,
as shown below.
20
3
10
200
30
4
80
12
23 x 14
The next step is to add up
the rows, putting the answer
in the boxes on the right.
20
3
10
200
30
230
4
80
12
92
23 x 14
Now add up the totals on the
right to give the answer.
20
3
10
200
30
230
4
80
12
92
322
Now you can work out multiplication
using the grid method, you will find long
multiplication easy!
This is a little different
from the grid method,
as the numbers are
set out in columns…
51 x 42
becomes
51
x 42
51 x 42
The first thing to do, is
multiply the tens of the
top number with the tens
and units of the bottom
number.
51
x 42
Remember what
we did using
the grid method?
51 x 42
50 x 40
50 x 2
Always write down the
multiplication you have
worked out next to
the answer.
51
x 42
2000
100
51 x 42
50 x 40
50 x 2
Next, multiply the
units of the top
number by the tens
and units of the
bottom number.
51
x 42
2000
100
51 x 42
50 x 40
50 x 2
1 x 40
1x 2
51
x 42
2000
100
40
2
Don’t forget to
write down the
multiplication
next to the
answer.
51 x 42
50 x 40
50 x 2
1 x 40
1x 2
51
x 42
2000
100
40
2
2142
The final step is
to add up the
column of
numbers and put
the total at
the bottom.
Try using long multiplication
to work out…
25 x 62
25 x 62
becomes
25
x 62
25 x 62
25
x 62
x
x
Remember:
The first step is to multiply the
tens of the top number with the
tens and units of the bottom
number.
25 x 62
20 x 60
20 x 2
x
x
The next step is to
multiply the units
of the top number
by the tens and
units of the bottom
number.
25
x 62
1200
40
25 x 62
20
20
5
5
x 60
x 2
x 60
x 2
25
x 62
1200
40
300
10
Now add up
the totals
and put
them at the
bottom.
25 x 62
20
20
5
5
x 60
x 2
x 60
x 2
25
x 62
1200
40
300
10
1550
You can now work out
calculations using
long multiplication.