> **Synthetic demonstration — not real data.**

# Study plan: Percentages for bookkeeping

- Goal: "I need to understand percentages properly for my bookkeeping course quiz. I can do 50% and 10% in my head but I get lost with things like 'what percent of 80 is 12' or percentage increase."
- Deadline: 2026-04-14
- Time available: 3 hours per week
- Starting point: Learner reports being able to calculate 50% and 10% mentally but gets confused when the percent is unknown ("what percent of 80 is 12") and with percentage increase. Plan builds on the stated strengths and targets those gaps using the supplied course notes.

## Plan

| Session | Topic | Length | Source |
|---|---|---|---|
| 1 | Percent means per hundred and finding the part | 60 min | Course notes (supplied) |
| 2 | Finding the percent and the whole | 60 min | Course notes (supplied) |
| 3 | Percentage increase and decrease, plus review | 60 min | Course notes (supplied) |

## Explanation: Percent means per hundred

Percent means "per hundred," so 25% means 25 out of every 100. The course notes give the formula **part = percent × whole**. Use it when you know the percent and the whole and need the part. When the percent is missing, rearrange to **percent = part ÷ whole**: divide the part by the whole to get the fraction, then multiply by 100 because percent means per hundred. For percentage change, the course notes give **percentage change = (new − old) ÷ old × 100**.

Worked example: "What percent of 80 is 12?"  
1. Identify part = 12 and whole = 80.  
2. Use percent = part ÷ whole.  
3. Compute 12 ÷ 80 = 0.15.  
4. Multiply by 100 → 15%.  
So 12 is 15% of 80.

## Practice

1. What is 25% of 200?
2. 18 is what percent of 60?
3. A bookkeeping cost rose from $40 to $52. What is the percentage increase?
4. What is 7.5% of 160?
5. A value fell from 150 to 120. What is the percentage decrease?

## Answers (keep separate)

1. 50
2. 30%
3. 30%
4. 12
5. 20%

## Progress notes

- Right: The learner already handles 10% and 50% mentally, so converting percents to decimals and using the basic part/percent/whole relationship should feel like a small extension.
- Revisit: Rearranging the formula when the percent or the whole is unknown, and setting up percentage change correctly with (new − old) ÷ old × 100.