Multiplying Large Numbers

Solve problems involving multiplication of large numbers by one- or two-digit numbers using efficient mental, written strategies and appropriate digital technologies (ACMNA100)

LO: To multiply large numbers
Know:

  • Multiplication facts up to 10 x 10

Understand:

  • multiplying numbers by whole numbers increases the value of a number.
  • dividing numbers by whole numbers decreases the value of a number.
  • Dividing can be thought of as “evenly dividing”
  • Dividing is the opposite of multiplying

Do:

  • I can multiply large numbers

Times Tables

Grid Method

Step 1: break 45 and 23 into their respective parts.
Step 2: write 40 and 5 at the top, 20 and 3 down the side.
Step 3: multiply 40 x 20 then 5 x 20 then 40 x 3 and 5 x 3
Step 4: Then add all of the sums together

Lattice Method

Step 1: Break down the numbers to their respective parts.
Step 2: write 2, 7, 8 at the top and 3 and 4 down the side
Step 3: split each of the cells into halves diagonally.
Step 4: work out each box accordingly, 8 x 3, 7 x 3, 2 x 3, 8 x 4, 7 x 4, 2 x 4
Step 5: add all numbers below each line
Step 6: Circle the outside numbers and re-write answer.

Long Multiplication

Step 1: Set up the “tower”
Step 2: multiply the first number accordingly 6 x 3, 6 x 5
Step 3: Don’t forget the “magic zero”
Step 4: multiply the second number accordingly 2 x 3, 2 x 5
Step 5: Add the numbers column by column

Multiplying Using Lines

Step 1: Draw lines to represent the numbers, 12 would break down to 1 and 2, 34 would break down to 3 and 4.
Step 2: Count the number of crosses that occur. Far right is your ones column, middle is your 10s column and far left is your 100s column. If there is anything over 10 you need to carry it over to the next column.

Multiplication Videos

Grid Method Video

Lattice Method Video

Long Multiplcation Method Video

Lines Method Video

Rainbow Method Video