PRACTICE: Addition

Start with the bigger number and count to the right as many times as the smaller number.

Locate where 43 is.

Jump 12 units to the right from 43. 12 is made up of 1 tens and 2 units. So we can jump to the right by 1 tens and then 2 units.

We end up at the number 55. So: 43 + 12 = 55

We will use the compensation strategy.

Plot the larger number, 49 on the number line.

We can see that 16 is 4 below 20 on the number line below.

Using the compensation strategy to add 16 to 49 we can add 20 and then take away 4.

So now we can jump to right by 2 tens from 49 to get 49 + 20=69.

And now we subtract 4 by jumping to the left by 4 to get 69 - 4=65.

49 + 16 = 65

Use the addition algorithm.

Write it in a vertical algorithm.\begin{array}{c} & & &2 &1 &9 \\ &+ & & &2 &9 \\ \hline & \\ \hline \end{array}

Add the units value first. So 9 + 9 = 18. Bring down the 8 and carry on 1 to the tens column.\begin{array}{c} & & &2 &\text{}^1 1 &9 \\ &+ & & &2 &9 \\ \hline & & & & &8 \\ \hline \end{array}

So for the tens place we have 1 + 1 + 2 = 4: \begin{array}{c} & & &2 &\text{}^1 1 &9 \\ &+ & & &2 &9 \\ \hline & & & &4 &8 \\ \hline \end{array}

Hundreds place: 2 + 0 = 2

\begin{array}{c} & & &2 &\text{}^1 1 &9 \\ &+ & & &2 &9 \\ \hline & & &2 &4 &8 \\ \hline \end{array}

So 219 + 29 = 248.