Calculators: changing the cells for the Sharp el-520w, el-531w, el-w535

The tutor tells how to change the batteries for the Sharp el-520w, el-531w, and el-w535.

Here are the cell requirements:

  • el-520w: two LR44 cells
  • el-531w: two LR44 cells
  • el-w535: one LR44 cell

Flipping any of the three models over, you’ll see a crease across the plastic near one end. The screws at that end are the ones to remove to change the cell(s).

I bought Sunbeam replacement cells in a pack of 8, I think from a dollar store. LR44 cells can vary widely in price, depending on where you buy them.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Spreadsheets: text rotation with Excel

The tutor tells how to rotate text in Excel.

Excel can rotate text at an arbitrary angle. In Home view, find the button that looks like . Clicking the little down arrow next to it, you’ll see a drop-down menu; at the bottom says Format Cell Alignment. Clicking that, you’ve an orientation tool that allows you to set degrees.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Geography: CIA World Factbook

The tutor shares findings about world population and life expectancy from the CIA World Factbook.

Now and then I like to drop by the CIA World Factbook. Today I got some surprising intel:

World life expectancy: 69 years (much higher than I expected)

Population growth rate: 1.08% (about half what I expected)

Happily, Canada is one of the ten least densely populated countries:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Octal logic: 6 AND 5 = 4

The tutor explains a consequence of octal logic.

Octal logic focuses on numbers in base 8. An octal number has the following form:

p(20)+q(21)+r(22)

which evaluates to

p(1)+q(2)+r(4)

where p,q,r have possible values 0 or 1 (“off” or “on”).

The number 6 is

0(1)+1(2)+1(4): q,r=1

The number 5 is

1(1)+0(2)+1(4): p,r=1

The AND operation puts a 1 only where both inputs already equal 1. From above, we see that for 6 and 5, only r is 1 in both. Since r is the coefficient of 4, we have 6 AND 5 = (1)4 = 4.

Source:

Grimaldi, Ralph P. Discrete and Combinatorial Mathematics. Don Mills: Addison-Wesley, 1994.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English: the meaning of coeval

The tutor shares his discovery of the word coeval.

According to the Oxford Canadian Dictionary(2005), coeval can be an adjective, meaning of the same period or age. It can also be a noun, meaning a person contemporary with another.

Perhaps one could say that two people graduating this year are coeval, or that they are coevals.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Spreadsheets: How to border a range of cells in Excel

The tutor tells how to set a border around a selected area in Excel.

Here’s how:

  1. Select the area around which you want a border, then right click.
  2. You’ll see a toolbar and a menu. On the toolbar, find the icon that’s a square divided in four. Click the downward arrow beside it.
  3. A dropdown menu will appear: at the bottom, click More Borders…
  4. In the pane that appears, you can select the style, thickness, color, etc, that you want. See next step for important info.
  5. In my experience, the order in which you set the options matters: For best results, select the style, then the color, then the outline, then OK. Otherwise, the border may not show the color, etc, that you desire.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Spreadsheets: How to border a selection in LibreOffice Calc

The tutor explains how to set a border around a range of cells in LibreOffice Calc.

Here’s what to do:

  1. Select the area around which you want a border.
  2. Find the icon that’s a square divided in four; it’s perhaps four in from the right. If you mouse over it, you’ll see Borders, add lines
  3. Click that icon, then select the style of border you want.

You’ll see a thin, black border around your selection. To customize that border, do the following:

  1. Make sure the range is still selected (or select it again).
  2. At the top of the screen, click Format, then Cells…
  3. Select the Borders tab. Therein, you’ll see where you can select the style, width, and color of the border.
  4. I find a border really doesn’t become obvious until it’s 1.25pt or more.
  5. Click OK to apply your choices.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Math: symbolic logic meets digital circuits: p→q means ¬A or B

The tutor translates p→q to the boolean expression ¬A or B.

In my beginning post about symbolic logic, I mention that the statement p implies q, also stated p→q, has the following truth table:

p q p→q
0 0 1
0 1 1
1 0 0
1 1 1

(I also mention, in that same post, the symbols and so on needed to understand basic logical expressions such as the ones herein.)

In digital logic (aka, digital circuits, boolean expressions, etc), ¬A or B has the same truth table:

A B ¬A or B
0 0 1
0 1 1
1 0 0
1 1 1

Neat, eh?

Source:

Grimaldi, Ralph P. Discrete and Combinatorial Mathematics, 3rd ed. Don Mills: Addison-Wesley Publishing Company, 1994.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Spreadsheets: Calculating fraction of a year: yearfrac() function

The tutor shows an example of how to use the yearfrac() function in Excel or LibreOffice Calc.

Example: Find the fraction of a year between January 10, 2016, and June 2, 2016.

Solution:

  1. In Excel or LibreOffice Calc, select a cell.
  2. Type the following:
    =yearfrac(date(2016,01,10),date(2016,06,02),1)
  3. Press Enter.

Hopefully you receive the answer 0.39344

The third parameter (which is set at 1 in the example above) can be set 0,1,2,3, or 4: the options include a 30-day month, a 360-day year, or the actual length of a given month and year, etc. If you leave it blank or zero, it uses the American 30-day month, 360-day year system. “1” means actual values of days.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Spreadsheets: which day in the year is this? -Calculated with Excel or LibreOffice Calc

The tutor tells how to find the number of a day in the year with Excel or LibreOffice Calc.

Today, October 21, 2016, is the 295th day of 2016. How do I know? Here are two ways:

  1. Counting the days in the remaining months, then subtracting from 366. (2016, being divisible by 4, is a leap year.) 366 – 31 (Dec) -30 (Nov) -10 (remaining Oct) =366 – 71 = 295.
  2. Taking today’s date, then subtracting Dec 31, 2015 from it, to get the days so far this year. This is done in Exel, or LibreOffice Calc, by selecting a cell, then entering the following:

    =today() – date(2015,12,31)

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.