# Activities

• • • ##### Subject Area

• Math: Elementary Math: Number Operations

• ##### Author K-5

60 Minutes

• ##### Device
• TI-10
• TI-15 Explorer™
• ##### Other Materials
This is Activity 2 from the EXPLORATIONS Book:
Integrating Handheld Technology into the Elementary Mathematics Classroom .

The following calculators can also be used for this activity:
TI-108
MathMate™

## Number and Operation Sense: Whole Numbers

#### Activity Overview

Students attain a basic understanding of numbers and number operations, developing number sense, and gaining fluency in arithmetic computation. They also learn to use the calculator to explore the mathematical principles behind the standard multiplication algorithm for multidigit numbers.

#### Before the Activity

• See the attached PDF file for detailed instructions for this activity
• Print pages 9 - 20 from the attached PDF file
• #### During the Activity

Distribute the pages to the class.

1-2-3-4-Challenge

• Use the four digits 1, 2, 3, 4, and any or all of the four operations: +, -, x, to form one or more expressions for each of the values 1 through 12
• Test your expressions on the calculator
• View expressions created for each value, and explore algebraic properties by comparing two different expressions for the same number
• Enter the expression for 12: 3 + 4 x 2 + 1 in the TI-108 calculator and MathMate, TI-10, or TI-15 calculator
• Observe that the TI-108 uses arithmetic logic - it computes in the order in which the operations are entered and displays the result as 15, and MathMate, TI-10, TI-15, and most other TI calculators use algebraic logic and employ the algebraic order of operations and display the result as 12
• Note that multiplying or dividing by 1 keeps the same number, adding or multiplying increases values, while subtracting and dividing decreases values

• Create the Greatest Product
• Using the five digits 1, 2, 3, 4, and 5 create a three-digit number and a two-digit factor that give the greatest product
• Try the problem again with the digits 2, 4, 6, 7, and 9
• Observe that the greatest product is formed by placing the greatest digit in the tens place of the two-digit factor
• Try the problem again with the digits 0, 3, 5, 6, 8, and compare the results

• Using calculators to assess whole number and operation sense
• Test a wide variety of sets of three consecutive whole numbers in order to look for a pattern in their sums
• Observe that the sums are divisible by 3
• Use the calculator to solve real world problems involving whole numbers and operations with whole numbers
• #### After the Activity

Review students results and re-teach concepts as necessary.