## Grocery shopping: calculation methods

Self-tutoring about ways to estimate a grocery bill: the tutor mentions some thoughts. When I get around to it, I don’t mind grocery shopping. One idea I hold to, though, is that one should have a pretty good idea of …

## Math: discount then tax

Tutoring math, everyday problems need easy methods when possible. The tutor mentions one. Let’s imagine a consumer buys an item with sticker price \$44, subject to 15% discount, then 12% tax. What is the final amount they will pay? One …

## Financial math: can time be negative?

The tutor answers a question that brought someone to his site. These days, Oracle Tutoring gets between 5000 and 6000 distinct visitors per month. Looking over the raw log entries of how some visitors arrived, I saw an inquiry yesterday …

## Solar energy: price per Watt

The tutor continues from his last post about the value of solar energy dollars. In my last post I discussed the Wattage one might expect from solar energy for \$100. Based on a graph from Scientific American, the equation for …

## Financial math: ordinary annuity versus annuity due

The tutor continues exploring annuities.   In my previous post I introduced the idea of an annuity with an example. That example had each payment at month’s-end; hence, it was an ordinary annuity. With an annuity due, the payment is …

## Financial math: annuities, part I

Financial math awaits many students.  The tutor introduces annuities. From the point of view of a typical consumer, an annuity is the reverse of a loan.  The consumer becomes the lender, while the institution pays them back, often with monthly …

## Financial math: interest rate conversions on the HP-10B

A lifetime ago, the tutor studied financial planning.  That’s when he got acquainted with the HP-10B. Of the financial calculators I know, the Hewlett-Packard HP-10B is potentially the easiest to use. One feature of particular value to anyone in financial …

## Consumer Education: the Consumer Price Index

When the tutor was in high school, a course called Consumer Education was mandatory. The beautiful, energetic high school students of today will, sooner or later, be workers. They will gain one kind of freedom at the expense of another. …