Describe how you would help your learners in a primary class to multiply the following using number line. 7 x 1/3, 10 x 2/5, 2 x 4/5, 3 x 1/4, 4 x 1/4.

Formula: $271 \times 1 = 271$

Substitute: $200 \times 1 = 200$, $70 \times 1 = 70$, $1 \times 1 = 1$

Simplify: $200 + 70 + 1 = 271$

Write 271 aligned to the right:

\begin{array}{r@{}r@{}r@{}r@{}r} & & & 2 & 7 & 1 \\ \times & & & & 3 & 1 \\ \hline & & & 2 & 7 & 1 \\ \end{array}

Formula: $271 \times 3 = ?$, then $\times 10$.

First, $271 \times 3$:

$1 \times 3 = 3$

$7 \times 3 = 21$ (write 1, carry 2)

$2 \times 3 + 2 = 8$

So, 813. Then shift: 8130.

Write 813 starting under the tens column:

\begin{array}{r@{}r@{}r@{}r@{}r@{}r} & & & & 2 & 7 & 1 \\ \times & & & & & 3 & 1 \\ \hline & & & & 2 & 7 & 1 \\ + & & 8 & 1 & 3 & & \\ \hline \end{array}

Formula: $271 + 8130 = ?$

Column by column, right to left:

Units: $1 + 0 = 1$

Tens: $7 + 3 = 10$ (write 0, carry 1)

Hundreds: $2 + 1 + 1 = 4$

Thousands: $8 = 8$

Simplify: 8401

\begin{array}{r@{}r@{}r@{}r@{}r@{}r} & & & & 2 & 7 & 1 \\ \times & & & & & 3 & 1 \\ \hline & & & & 2 & 7 & 1 \\ + & & 8 & 1 & 3 & 0 & \\ \hline & 8 & 4 & 0 & 1 & & \\ \end{array}

8401