Lesson 4

Estimating with Multiplication

Est. Class Sessions: 2

Daily Practice and Problems

Teacher Notes
X

TIMS Challenge

This item can be used as a Problem of the Week.

Calculators are appropriate for solving these problems.

  1. 91 × 63 = 5733
  2. 9 × 1 − 6 − 3 = 0
  3. Answers will vary. Some possible responses:
    1 = 9 − 6 − 3 + 1
    2 = 6 × 3 ÷ 9 × 1
    3 = 6 × 3 ÷ 9 + 1
    4 = 36 ÷ 9 × 1
    5 = 36 ÷ 9 + 1
    6 = 9 − 6 ÷ 3 − 1
    7 = 9 − 6 ÷ 3 × 1
    8 = 9 − 6 ÷ 3 + 1
    9 = 9 ÷ 3 ÷ 1 + 6
    10 = 6 × 3 − 9 + 1
  4. Answers will vary. Some possible responses:
    11 = 9 × 3 − 16
    12 = (9 − 6 + 1) × 3
    13 = 9 − 3 + 1 + 6
    14 = (none)
    15 = 6 × (3 + 1) − 9
    16 = 31 − 6 − 9
    17 = 9 × 6 ÷ 3 − 1
    18 = 9 × 6 ÷ 3 × 1
    19 = 9 × 6 ÷ 3 + 1
    20 = 9 × 3 − 6 − 1
    21 = 9 × 3 − 6 × 1
    22 = 9 × 3 − 6 + 1
    23 = 39 − 16
    24 = 3 × (6 − 1) + 9
  5. Using a digit more than once:
    14 = 9 − 3 + 1 + 6 + 1

N. Operation Target: 1, 3, 6, 9

Play Operation Target.

  • Use the four digits 1, 3, 6, 9, and the four operations (+, −, ×, ÷) to make as many numbers as you can.
  • You must use each of the four digits exactly once.
  • Use any operation once, more than once, or not at all.
  • You may use 2-digit numbers and parentheses.
  • No fractions are allowed.

For example: 1 + 63 ÷ 9 = 8

  1. What is the largest number you can make?
  2. What is the smallest number you can make?
  3. Make the numbers 1 to 10.
  4. See how many numbers from 11 to 24 you can make.
  5. If there are numbers from 11 to 24 you could not make, try using one of the digits more than once.