PRACTICE: Addition and subtraction

Use the subtraction algorithm method.

Write it in a vertical algorithm.\begin{array}{c} & &7 &9 &6 \\ &- &4 &2 &9 \\ \hline \\ \hline \end{array}

Begin with the units column. We can see that 6 is less than 9, so we need to trade 1 ten from the tens column. This gives us 16 - 9 = 7 in the units column and 9 tens becomes 8 tens in the first row. \begin{array}{c} & &7 &8 &\text{}^1 6 \\ &- &4 &2 &9 \\ \hline & & & &7 \\ \hline \end{array}

For the tens place: 8 - 2 = 6. \begin{array}{c} & &7 &8 &\text{}^1 6 \\ &- &4 &2 &9 \\ \hline & & &6 &7 \\ \hline \end{array}

For the hundreds place: 7 - 4 = 3. \begin{array}{c} & &7 &8 &\text{}^1 6 \\ &- &4 &2 &9 \\ \hline & &3 &6 &7 \\ \hline \end{array}

So 796 - 429 = 367.

Use the vertical algorithm method.

Write it in a vertical algorithm.\begin{array}{c} & & &7 &6 &8 &1 \\ &+ & &9 &2 &7 &3 \\ \hline \\ \hline \end{array}

Add the units column. \begin{array}{c} & & &7 &6 &8 &1 \\ &+ & &9 &2 &7 &3 \\ \hline & & & & & &4\\ \hline \end{array}

Add the tens column: 8 + 7 = 15, so we bring down the 5 in the tens column and carry the 1 to the hundreds column:\begin{array}{c} & & &7 &\text{}^1 6 &8 &1 \\ &+ & &9 &2 &7 &3 \\ \hline & & & & &5 &4\\ \hline \end{array}

Add the hundreds column. \begin{array}{c} & & &7 &\text{}^1 6 &8 &1 \\ &+ & &9 &2 &7 &3 \\ \hline & & & &9 &5 &4\\ \hline \end{array}

Add the thousands column: 7 +9 = 16, so we bring down the 6 in the thousands column and carry the 1 to the ten thousands column:\begin{array}{c} & &\text{}^1 &7 &\text{}^1 6 &8 &1 \\ &+ & &9 &2 &7 &3 \\ \hline & & &6 &9 &5 &4\\ \hline \end{array}

Add the ten thousands column. \begin{array}{c} & &\text{}^1 &7 &\text{}^1 6 &8 &1 \\ &+ & &9 &2 &7 &3 \\ \hline & &1 &6 &9 &5 &4\\ \hline \end{array}

So 7681 + 9273 = 16\, 954.

Use the standard algorithm method.

Write it in a vertical algorithm.\begin{array}{c} & & &5 &5 &8 &7 &2 \\ &- & & &2 &6 &1 &9 \\ \hline & \\ \hline \end{array}

In the ones column we can see that 2 is less than 9, so we need to trade 1 ten from the tens place.

So we get 12-9=3 in the ones column and 7 tens becomes 6 tens in the first row.\begin{array}{c} & && 5&5 &8 &6 &\text{}^1 2 \\ &- && &2 &6 &1 &9 \\ \hline & && & & & &3\\ \hline \end{array}

In the tens column, we have 6-1=5:\begin{array}{c} & && 5&5 &8 &6 &\text{}^1 2 \\ &- && &2 &6 &1 &9 \\ \hline & && & & & 5 &3\\ \hline \end{array}

In the hundreds column, we have 8-6=2:\begin{array}{c} & && 5&5 &8 &6 &\text{}^1 2 \\ &- && &2 &6 &1 &9 \\ \hline & && & & 2& 5 &3\\ \hline \end{array}

In the thousands column, we have 5-2=3:\begin{array}{c} & && 5& 5 &8 &6 &\text{}^1 2 \\ &- && &2 &6 &1 &9 \\ \hline & && & 3& 2& 5 &3\\ \hline \end{array}

And for the ten thousands place 5-0=5:\begin{array}{c} & && 5& 5 &8 &6 &\text{}^1 2 \\ &- && &2 &6 &1 &9 \\ \hline & && 5& 3& 2& 5 &3\\ \hline \end{array}

So the answer is:55\,872 - 2619 = 53\,253