Chapter 7 Decimals Worksheet - New Century Maths Page 21
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38Working mathematically
Applying strategies and reflecting: Multiplication estimation game
This is either a game for two players, or a class team game.
Players should copy this table into their books or print it from the CD-ROM, but
should not commence calculating.
Correct answer
Multiplication
Estimation
Points
from calculator
42 × 3.5
a
5.1 × 2.4
b
1.6 × 7.3
c
3.8 × 6.2
d
2.2 × 8.8
e
7.5 × 3.2
f
5.6 × 5.7
g
2.6 × 5.1
h
9.3 × 3.9
i
4.8 × 3.3
j
Total
Rules
Step 1: You each have a two-minute time limit in which to estimate all the answers for
the 10 multiplication questions in the table, correct to one decimal place.
Step 2: On the instruction ‘Go’ given by your partner, you begin to write the estimates
for the multiplication questions in your table.
Step 3: After two minutes, stop. Then the other person completes Step 2.
Step 4: Use a calculator to find the exact answers, and score yourself for each
multiplication.
• 5 points for each estimate within 0.1 of the correct answer.
• 4 points for each estimate within 0.2 of the correct answer.
• 3 points for each estimate within 0.3 of the correct answer.
• 2 points for each estimate within 0.4 of the correct answer.
• 1 point for each estimate within 0.5 of the correct answer.
• 0 points if the estimate is more than 0.5 from the correct answer.
Step 5: Total your points, and compare your total with that of your partner.
Investigate further
1 Did you tend to overestimate or underestimate?
2 Now make up and try your own set of 10 decimal multiplications. See if you perform
better with practice.
Spreadsheet
7-03
3 Use this link to try an Excel version of this game.
Multiplication
game
218
NEW CENTURY MATHS 7
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