1. Decimals - ordering and rounding
N1.1 Extension Starter
Explain this statement. On my calculator six million plus is six million!
How can you use your calculator to work out this calculation exactly?
Challenge
How can you work out × exactly using a calculator?
Preamble An activity to make pupils a little more aware of the limitations of the calculator and to recap on some paper and pencil methods.
Possible content Place value, non-calculator methods for calculation.
Resources
Calculators.
Solutions/Notes The calculator gives = because the calculator is not able to display enough digits to give the exact answer. One way to work out the addition on a calculator is to divide up the numbers (indicated by vertical lines).
| and 984 |
Begin by working out = Add together the digits from the front of the numbers: =
Remember that you need to add nine zeroes to the end of this. Then you get =
In the challenge pupils will need to split each number of the multiplication into two or more parts, perform individual multiplications (remembering to put on the extra zeroes) and then combine the answers using addition.
The final answer is