# Author’s Notes

The Little Green Math Book presents a compilation of tricky but basic math. It is especially designed to help readers build their math thinking skills in the shortest possible time frame. Such thinking skills make it much more likely that a person will be able to approach basic math in a conceptual way and grasp those key principles that act as themes to bind related problems.

Consider the following ten questions are excerpted from the opening quiz appearing on pages 13–14 of the paperback book. Each statement is to be marked true or false.

1. If the ratio of females to males at a business conference is 1:2, then the percentage of people who are female at this conference is 50%.

2. For a given product, markup is always a smaller percentage than margin.

3. A couple charged \$132 on their credit card to pay for a meal while dining out. This \$132 figure included a 20% tip which was paid on top of the price of the meal, which already included a sales tax of 10%. The actual price of the meal before tax and tip was \$92.40.

4. Ratios are useful tools that tell us some­thing about actual size or value.

5. Multiplying a number by 1.2 is the same as dividing that same number by 0.8.

6. Break-even occurs exactly where profit equals total fixed costs.

7. A store item that has been discounted first by 20% and then by 30% is now selling at 50% of its original price.

8. At a summer party attended by exactly 100 persons, invitees were asked to consider making a small donation to one of Charity A or Charity B or to both charities. Sixty persons donated only to Charity A and 35 persons donated only to Charity B, while 20 persons donated to neither Charity A nor Charity B. Based on this information, we can conclude that 25 persons donated to both Charity A and Charity B.

9. If product A is selling for 20% more than product B, then the ratio of the selling price of product A to the selling price of product B is 100% to 80%.

10. Data with a high standard deviation is “bunched.” Data with a low standard deviation is more “spread out.”