Practice Tests

Chapter 8: Computation with Whole Numbers

1. Why is estimation an essential part of learning how to add, subtract, multiply and divide?
2. Use an example or two to show how mental math algorithms promote number sense.
3. To calculate 341 – 189, a student subtracts 200 from 341 and then another 11 since 189 is 11 less than 200. What might you say to prompt that student to see his or her error?
4. You want to introduce students to how to multiply 3–digit number by 1-digit numbers. How would you start them off?
5. One of the difficulties students have is that when adding numbers, each digit in the first number is combined with only one digit in the second number. But this is not the case when multiplying. How could you help students understand why this is the case?
6. Which division algorithm would you introduce to students first? Explain why.
7. Select a non-traditional division algorithm and explain the benefit of using it, as compared to the traditional algorithm.
8. One way to divide is to break up the dividend into parts that are more obvious multiples of the divisor, e.g. 415 ÷ 3 as 300 ÷ 3 + 90 ÷ 3 + 15 ÷ 3 + 10 ÷ 3. How would you explain the value of this approach and why it is okay to use?
9. Why is it important to give specific attention to subtracting from and dividing numbers with many zeroes in them, e.g. 4002?