Q&A #2599

Teachers' Lounge Discussion: Classroom Openers

T2T || FAQ || Ask T2T || Teachers' Lounge || Browse || Search || T2T Associates || About T2T

View entire discussion
[<< prev] [ next >>]

From: Joe

To: Teacher2Teacher Public Discussion
Date: 2004071820:54:49
Subject: Re: Re: Re: Classroom Openers

I am reminded of an old trick that might amuse you and egage the
students.  Have them pick a two digit number...

Now begin to play with them; having them add, multiply, etc. to the
number.  In the end you can have them reach a specific number or the
one they chose originally.

You can work out your routine ahead of time by using algebra.

Let the first digit of any number be A and the second digit (or one's
column) be B.  Then any student choice will equal 10A+B.

Now play with the algebra.

Divide their number by 2...


multiply it by 8


subtract 20 and then divide by 2 : (40A+4B-20)/2 = 20A+2B-10

Add 10

multiply by three

divide by six


Playing with three digits might mean letting them use their calculator
and just use 100A+10B+C in your calculations.

Post a reply to this message
Post a related public discussion message
Ask Teacher2Teacher a new question

[Privacy Policy] [Terms of Use]

Math Forum Home || The Math Library || Quick Reference || Math Forum Search

Teacher2Teacher - T2T ®
© 1994- The Math Forum at NCTM. All rights reserved.