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Activity Overview |
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Students compute multiples of 9, 99, 999, and so forth, search for patterns in the products, and write generalizations of those patterns.
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Before the Activity |
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See the attached PDF file for detailed instructions for this activity
Print pages 11 - 13 from the attached PDF file for the class
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During the Activity |
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Distribute the pages to the class.
Follow the activity procedures:
Multiply numbers 1 - 12 by nine and record the products
Find the sum of digits in the products and observe that it is 9
Multiply numbers 1 - 5 by 9 and by 79 and record the products
Understand that in the product, the digit in the units and tens place is the number itself; and the digits in the hundredth and thousandth place are the product of 7 and the number
Predict the product of 9 and 79 with other single digit numbers and check the predictions
Note that the sum of the digits of each product is a multiple of 9, since 9 is a factor
Multiply 2 digit numbers by 99 and record the product
Realize that the product is 100 times the number minus that number
Use this statement to predict products
Multiply a 2-digit number by 999 and recognize that each product is 1000 times the first factor minus the first factor
Observe that when a single digit is divided by 9, the digit repeats itself after the decimal point
Notice that when a 2-digit number is divided by 9, the digit repeated after the decimal point is the sum of the digits of the original number
Divide a single digit number by 99 and observe that the decimal has the given number repeating
Divide a 2-digit number by 99, and observe that the decimal has those 2 digits repeating
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After the Activity |
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Students complete the activity pages and answer questions.
Review student results
As a class, discuss questions that appeared to be more challenging
Re-teach concepts as necessary
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Other Downloads |
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view standards alignment
view textbook alignment
Subject Area:
Math : PreAlgebra : Number Sense and Operations
Author:
Texas Instruments
Level:
5-8
Activity Time:
60 Minutes
Device:
TI-30Xa, TI-30X IIB, TI-30X IIS, TI-34 II Explorer Plus™
Apps:
Software:
Accessories:
Other:
This is Activity 2 from the EXPLORATIONS Book:
Investigating Mathematics with Calculators in the Middle Grades
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