Adding Multiple Numbers

Objectives

To understand how we can simplify calculations involving multiples of 10 and 100.

To gain confidence in applying strategies for calculating larger numbers.

Resources

Abacus 4 Textbook 1 | Squared paper | Timestables (TopMarks)

Today's Lesson

Main Activity

If your student has been learning the 2 times table this week, ask them to recite it and to answer random questions on it.

Turn to page 10 in Abacus 4 Textbook 1.

Watch the ‘Adding several numbers’ video which looks at strategies to solve these types of questions.

After watching the video, ask your student to remind you of the main tips for adding several numbers more easily.

Tip 1: Remember to look for number bonds (or even doubles) to help you add the numbers.

Tip 2: When adding tens or hundreds in Q4-9, ignore the zeros to start with and simply count the numbers as single digits. If we use this method, we must be sure to then add 1 zero for the tens numbers or 2 zeros for the hundreds numbers back at the end to find the final answer. E.g. Q4 - We are really saying 5 tens + 3 tens + 6 tens + 2 tens = 16 tens to get our answer.

Run through more examples with your student until they are confident in identifying pairs of numbers to easily add.

Ask your student to copy and complete the page, remembering to write each digit and symbol in its own square.

Note: The same principle can be applied to multiplications.

For example:

3 x 60 =

If we ignore the zero and work out that 3 x 6 = 18. In doing this, we have divided 60 by 10.

We then need to adjust the answer by multiplying by 10, effectively adding the zero back onto to our answer:

3 x 60 = 180

Citations

[1] www.topmarks.co.uk