# Tag Archives: announcement

## IMPORTANT – Bring Written Work Chp 4-5 to class on Thursday

Hi everyone,

If you picked up your (graded) written work from Chapters 4 and 5 today, please bring it with you on Thursday to class — I need to record your score in my gradesheet, or you will not get credit for the assignment. Ā Oops!

Thanks,

Prof. Reitz

## Exam Review 2 UPDATE – review of division and remainders

Hi everyone,

First, the answer key for the Exam 2 review is now complete (it follows the questions in the Review document). Ā Second, you will notice that there are a few places (especially in problems 8 and 12) that I use basic facts aboutĀ remainders when one number is divided by another. Ā These are facts that you understand intuitively from working with dividing numbers, but it might help to have them stated explicitly. Ā This is the basic fact about dividing and remainders:

Fact (The Division Algorithm). Ā Given two integersĀ a andĀ b with $b>0$, there exist unique integersĀ q andĀ r for which $a=qb+r$ and $0\leq r .

What does this mean? Ā It expresses the fact that when we divide one integerĀ a by another integerĀ b, and it will go in some number of timesĀ qĀ with a remainder ofĀ r. Ā The remainder rĀ must be less than the numberĀ b that we are dividing by. Ā If the remainder is zero, then b dividesĀ a (becauseĀ $r=0$ means $a=qb$), and if the remainder is not zero, thenĀ b does not divideĀ a.

-Prof. Reitz

## Followup on Today’s Lecture (Tues 10/8)

Hi everyone,

In the homework from today, the final two problems (#15, 16) use an idea called “Proof by cases” (considering different possible situations within your proof). Ā  Ā To complete these two problems, read Page 96 (starting with “4.4 Cases” and ending at the end of the first proof, at the bottom of the page). Ā Bring your questions on Thursday!

-Prof. Reitz

## Office hours today (10/4): 12pm-1pm

Hi everyone,

Office hours today will be from 12pm-1pm (I will also be able to answer a quick question or two right after class).

-Prof. Reitz

## Problems with our OpenLab site

Hi everyone,

A number of you have pointed out that our site is having problems – I’ve submitted a bug report, and will keep you posted. Ā Don’t worry – if it’s not resolved soon I’ll extend the deadline for OpenLab assignment #2.

Sorry for the trouble!

Prof. Reitz

## The review sheet is too darn long

This review sheet is rather long – because of this, I’ve marked certain problems Ā as optional (denoted with a double asterisk **). Ā If you have only a limited time for review, do the other problems first. Ā If you have a little extra time, the ** problems are good practice.

Optional Problems: Ā 1b, 2d, 4bf, 5efij, 6ae, 7c, 8d, 10a, 12b

## Office hours today are all messed up

Hi everyone,

Due to several meetings (the curse of a big institution), my regularly scheduled office hours will be all messed up today. Ā I’ll be available:
– Directly after class for about 12 minutes (until 11:27)
– From 12:30-1:00

If need more time with me, please let me know either at the end of class or by email, and I’ll do my best to find a time that works

.Apologies for the late notice,
Prof. Reitz