RIC-0563 Developing algebraic thinking
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PLACE VALUE PICKS<br />
Teacher’s notes<br />
Place value<br />
picks 7<br />
For the greatest sum in Place value picks 7, we know that the digit in<br />
the thousands place of the sum is 1. Likely choices of 9 and 8 in the<br />
hundreds place again cause duplicate digits in other places. Using ‘Guess<br />
and check’, a solution can be found:<br />
Greatest sum<br />
+<br />
8 4<br />
7 5<br />
1 6 0<br />
9<br />
3<br />
2<br />
The least sum also has a 1 in the thousands place. A desirable least<br />
sum would have the 0-tile in the hundreds place and a 2-tile in the tens<br />
place, thus requiring the sum of the digits in the hundreds place to be<br />
10 with trading.<br />
Least sum<br />
+<br />
4 8<br />
5 3<br />
1 0 2<br />
9<br />
7<br />
6<br />
Place value<br />
picks 8<br />
Subtraction is involved in Place value picks 8. To find the greatest<br />
difference, merely place the greatest digits 9, 8, and 7 in the known sum<br />
(minuend) in decreasing order. The least digits 0, 1, and 2 need to be<br />
reordered in the known addend (subtrahend).<br />
Greatest difference<br />
–<br />
9 8<br />
1 0<br />
8 8<br />
7<br />
2<br />
5<br />
The least difference can be found in five different ways, although only<br />
the hundreds digits change.<br />
Least difference<br />
–<br />
7 0<br />
6 9<br />
1<br />
8<br />
–<br />
6 0<br />
5 9<br />
1<br />
8<br />
–<br />
5 0<br />
4 9<br />
1<br />
8<br />
–<br />
4 0<br />
3 9<br />
1<br />
8<br />
–<br />
3 0<br />
2 9<br />
1<br />
8<br />
3<br />
3<br />
3<br />
3<br />
3<br />
R.I.C. Publications ® www.ricgroup.com.au DEVELOPING ALGEBRAIC THINKING 13<br />
ISBN 978-1-74126-088-5
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