Lesson

Do you know how to follow an algorithm to solve a problem?

We are going to add these two numbers together, using the addition algorithm below:

37+46

Add the units.

Is the result at least 10?

If no - GO TO step 3.

If yes - regroup into tens and units, then GO TO step 3.

Add the tens.

Is the result at least 100?

If no - GO TO step 5.

If yes - regroup into hundreds and tens, then GO TO step 5.

Write the final answer by adding the hundreds, tens and units.

a

Which two numbers will be added in step 1?

Worked Solution

b

Complete step 1: Add the units.

Worked Solution

c

What do we need to do at step 2?

Worked Solution

d

Regroup 13 into tens and units:

13 = ⬚+⬚

Worked Solution

e

Now complete step 3: Add the tens.

Worked Solution

f

What do we need to do at step 4?

Worked Solution

g

Complete step 5: Write the final answer by adding the hundreds, tens and units.

Worked Solution

Idea summary

We can use algorithms to add or subtract numbers.

Following algorithms allows us, or computers, to perform tasks. It's important that when you follow an algorithm you do each step.

Follow this algorithm.

a

Start with the number 16.

Add 5 to 16.

Worked Solution

b

Double your answer to part (a).

Worked Solution

Idea summary

When writing out the steps in an algorithm, you need to make sure each step is clear and that you give the correct order.

Follow a mathematical algorithm involving branching and repetition (iteration)