Stage: 2 Challenge Level: 
Why do this problem?
This problem is a good context in which to discuss different,
and perhaps most efficient, methods of calculation.
Key questions
Why don't you try adding all the one-digit numbers
first?
Can you describe what you did?
Are there any quicker ways of doing it?
Possible support
Learners could find the sum of the one-digit whole numbers
first and then the two-digit whole numbers instead.
Investigations. Addition & subtraction. Trial and improvement. Place value. Combinations. Working systematically. Factors and multiples. Interactivities. Generalising. Multiplication & division.
Published December 1999.
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