How do I multiply a triple digit number by a double digit?

1
How do I multiply a triple digit number by a
double digit?
142 x 12 ?
267 x 19 ?
145 x 67 ?
243 x 15 ?
Im sure that youll agree that there are many
methods that we can use. Which method do you feel
most comfortable with? Try your method to solve
one of the problems on this page. When you are
finished, explain your method to your partner.
142 x 14 ?
156 x 14 ?
262 x 15 ?
2
Heres a new method for you to try!
My problem is 145 x 13 ?
Step one Break the numbers up into their
different parts. 145 100 40 5 13 10 3
Step two Fill the numbers onto a grid like this.
100
40
5
x
10
3
3
Step 3 Begin to cross multiply each number
filling the answer into the grid. (This is just
like filling in a multiplication square.)
100
40
5
x
10
1000
400
50
3
300
120
15
Step 4 Add up each row of numbers and put your
total at the side of the column.
100
40
5
x
1450
1000
400
50
3
300
120
15
435
4
Step 5 Simply add the two numbers together to
get your final answer.
1 4 5 0 4 3 5 1 8 8 5
How easy is that?
Challenge! Can you use this new method to solve
the problem below? 134 x 15 ?
Therefore 145 x 13 1885
5
We can use this grid to solve problems together.