Changes, Highs, and Lows
This is a level 4 number activity from the Figure It Out series. It relates to Stage 7 of the Number Framework.
add and subtract using place value knowledge whole numbers and decimals
The students could use calculators to check the results of what went on in their heads. If they are having difficulty, you could look at Number, Figure It Out, Level 3, pages 2–3, Activity Three. The students could do these easier exercises as a warm-up.
To determine the winner of the game in this activity, the students need to add up the numbers for each player to date and then consider the impact of drawing particular cards.
They need to realise that there are only three cards of each digit in the pack, and from this, they can work out the possibility of certain digits being drawn. For example, all the 5s and all the 9s have already been drawn, but only one 1 and one 8 have been drawn.
When the students play this game, encourage them to think of the strategies that will give them the best score. For example, to gain the highest score, they should try to put the largest digits in the positions that have the highest place value.
Answers to Activity
1. 2 033
2. a. Add 2 200.
b. Add 2.
c. Subtract 12 345.
d. Subtract 5.
e. Subtract 3.61.
f. Add 0.05.
g. Subtract 50.324.
h. Subtract 2.997.
3. Problems will vary.
1. Mike will win (no matter what card he picks up) if Christine gets a card that is less than 5 to fill her tens . Otherwise, Christine will win. Remember that there are only three of each digit card, so there are no 5 or 9 cards left. If Mike picks up a 2, 3, 4, 6, or 7 in his turn (he started first, so he has first turn now), that would use up
all three of those cards.
2. A game of High Wins and a game of Low Wins