In this lesson, we will learn to estimate using derived facts and then adjust them to calculate the answer. We will then be able to solve a range of problems selecting suitable strategies and giving reasons for our choices.
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Which of the following methods for answering a multiplication questions is NOT a mental strategy?
Array models
Blank number line
Marked number line
Correct answer: Short multiplication
Short multiplication
Q2.
Today we discussed distributive law in relation to multiplication. But which of the following number sentences does NOT correctly represent distributive law?
13 x 24 = 10 x 24 + 3 x 24
19 x 17 = 19 x 10 + 19 x 5 + 19 x 2
Correct answer: 26 x 14 = 20 x 10 + 6 x 4
26 x 14 = 20 x 10 + 6 x 4
32 x 7 = 30 x 7 + 2 x 7
Q3.
Which of the following representations would be efficient for the calculation 317 x 23?
Correct answer: Array models
Array models
Cuisenaire Rods
Dienes
Q4.
For which of these calculations would you consider using a mental strategy and NOT a written method?
Which of the following number sentences would be the most efficient choice to use when estimating 237 x 4
200 x 4
230 x 4
235 x 4
Correct answer: 240 x 4
240 x 4
Q2.
Which estimation is correct for the calculation 192 ÷ 8?
190 ÷ 8
192 ÷ 10
200 ÷ 10
Correct answer: 200 ÷ 8
200 ÷ 8
Q3.
I rounded a calculation and got the estimated answer of 560. But what was my original sum?
109 x 4
131 x 4
Correct answer: 138 x 4
138 x 4
152 x 4
Q4.
Which of the following calculations would provide you with the value indicated on the marked number line after it is rounded to create an estimated answer?
