What you'll learn
Most GED math questions are word problems that take two, three or four steps: find a total, subtract it from what you paid, divide by the number of people, round to whole boxes. In this lesson you will learn:
- a simple 4-step plan for any word problem;
- how to translate words like each, per, left, in all into +, -, \times, \div;
- how to handle money, rates (per hour, miles per gallon, price per pound) and fixed fees;
- when to round up, round down, or keep decimals;
- how to work backwards from a final amount to a starting amount;
- how to compare two options (which plan or package is cheaper).
Why it matters on the GED: multi-step problems with whole numbers, fractions and decimals are everywhere on the test, and each step is a place to slip. A clear plan, written step by step, is what turns "I know the math" into points.
In real life: this is exactly the math of a paycheck, a grocery bill, a road trip budget or a flooring estimate.
Words to know
- Total / in all / altogether / combined — usually add (or multiply equal groups): 3 shirts at $12 each cost 3 \times 12 = \$36 in all.
- Difference / left / remaining / change / how much more — usually subtract: $50 − $36 = $14 change.
- Each / per / for every — signals a rate; multiply to get a total or divide to get the rate: $45 for 3 hours is $15 per hour.
- Split equally / shared / average — divide: $72 shared by 6 people is $12 each.
- Rate — a comparison of two different units: 28 miles per gallon, $3.60 per gallon.
- Unit price — price for one unit: $5.76 for 24 bottles is \$5.76 \div 24 = \$0.24 per bottle.
- Fixed fee (flat fee) — a one-time charge that does not depend on how much you use: a $75 service call.
- Estimate — a rounded, quick answer used to check reasonableness: \$3.459 \times 12.6 \approx \$3.50 \times 13 = \$45.50.
- Work backwards — start from the final result and undo each step in reverse order.
1. A 4-step plan for every word problem
1. Understand. Read the question twice. Underline what is being asked ("how much change", "how many boxes", "cost per person"). Circle the numbers you need — some numbers may be extra information.
2. Plan. Decide the steps in order, in words, before calculating. For example: "find the cost of the cheese, find the cost of the apples, add them, subtract from $50."
3. Solve. Do one step at a time and label each result with its unit ($, gallons, hours). Keep full decimals until the end.
4. Check. Does the answer answer the question that was asked? Is it reasonable (estimate)? Can you plug it back in?
Translating words into operations
| Words in the problem | Operation | Example |
|---|---|---|
| total, sum, in all, combined, increased by | + | 43.50 + 8.50 |
| difference, left, remaining, change, fewer, decreased by | - | 50 − 21.55 |
| each, per, times, of (with fractions), for every | \times | 3 × $14.50 |
| split, shared equally, per (to find a rate), how many fit | \div | $72 ÷ 6 |
Words are clues, not rules. "Per" can mean multiply ($15 per hour for 8 hours → 15 \times 8) or divide ($120 for 8 hours → 120 \div 8 dollars per hour). Always ask: am I finding a total or finding a rate?
2. Money, rates and the GED formula sheet
Two formulas from the GED formula sheet do most of the work in real-world problems:
- Total cost = (number of units) × (price per unit)
- Distance = rate × time
Chains of rates. Many problems link two rates. A road trip: miles ÷ (miles per gallon) = gallons; gallons × (price per gallon) = cost.
245\text{ mi} \div 35\tfrac{\text{mi}}{\text{gal}} = 7\text{ gal} \qquad 7\text{ gal} \times \$3.80 = \$26.60Paychecks. Pay = hourly rate × hours. With mixed numbers, convert first: 6\tfrac{3}{4}\text{ h} = 6.75\text{ h} (since \tfrac{3}{4} = 0.75, not 0.34).
Fixed fee + rate. A plumber charges a $75 call fee plus $45 per hour. For h hours: \text{cost} = 75 + 45h. Four hours cost 75 + 45 \times 4 = 75 + 180 = \$255. The fee is added once, not once per hour.
Unit price comparisons. To find the better buy, divide each price by its quantity and compare the unit prices. The bigger package is often — but not always — cheaper per unit.
Money answers are rounded to the nearest cent at the end. Rounding early can make you a cent or more off, which may not match the answer choices.
3. Rounding in context and working backwards
Round to whole items — but which way? The situation decides, not the usual "5 or more" rule.
| Situation | Round | Example |
|---|---|---|
| You must buy enough (boxes of tile, cans of paint, buses) | up | 8.2 boxes needed → buy 9 |
| You can only make or fill complete ones (servings, full bags) | down | 6.7 servings → 6 full servings |
| Money | to the cent | $43.5834 → $43.58 |
Working backwards. When a problem gives the end result and asks for the start, undo each step in reverse order with the opposite operation.
Example: Jo had some money. She spent $15 on lunch, then spent half of what was left on a shirt. She has $20 left. How much did she start with?
- Last step was "spend half" → undo by doubling: 20 \times 2 = 40.
- First step was "spend $15" → undo by adding: 40 + 15 = 55.
- She started with $55. Check forwards: 55 - 15 = 40; half of 40 is 20 spent; 40 - 20 = 20 left ✓.
Comparing options. For "which is cheaper" questions, compute the full cost of every option for the same situation, then compare. Don't stop after the first option that "seems" cheap.
Formulas (on the GED formula sheet)
\text{total cost} = (\text{number of units}) \times (\text{price per unit}) d = rt \qquad (\text{distance} = \text{rate} \times \text{time})Rearranged versions you will use constantly:
\text{price per unit} = \frac{\text{total cost}}{\text{number of units}} \qquad t = \frac{d}{r} \qquad \text{gallons used} = \frac{\text{miles}}{\text{miles per gallon}}Fixed fee plus a rate: \text{cost} = \text{fee} + (\text{rate}) \times (\text{amount}).
The total cost formula and distance = rate × time are on the GED formula sheet. The rearranged versions and the fixed-fee model are not printed — you build them from the originals by undoing multiplication with division.
Example 1 (easy): a grocery total
Maya buys 3 pounds of apples at $1.29 per pound and 2 gallons of milk at $3.49 per gallon. What is her total?
- Apples: 3 \times 1.29 = 3.87.
- Milk: 2 \times 3.49 = 6.98.
- Total: 3.87 + 6.98 = 10.85.
Answer: $10.85
Check: Estimate 3 \times \$1.30 + 2 \times \$3.50 = \$3.90 + \$7.00 = \$10.90 — very close ✓.
Example 2 (word problem): road-trip gas
A car gets 35 miles per gallon. Gas costs $3.80 per gallon. How much will the gas cost for a 245-mile trip?
- Gallons needed: 245 \div 35 = 7 gallons.
- Cost: 7 \times 3.80 = 26.60.
Answer: $26.60
Check: Work backwards: \$26.60 \div \$3.80 = 7 gallons; 7 \times 35 = 245 miles ✓.
Example 3 (word problem): buying whole packages
A family reunion has 75 guests. Each guest will get 2 hot dogs. Buns come in packs of 8 for $2.79 a pack. How much will the buns cost?
- Buns needed: 75 \times 2 = 150.
- Packs: 150 \div 8 = 18.75. You can't buy part of a pack, and 18 packs (144 buns) is not enough, so round up to 19 packs.
- Cost: 19 \times 2.79 = 53.01.
Answer: $53.01
Check: 19 packs hold 19 \times 8 = 152 \ge 150 buns ✓, and 18 packs hold only 144 ✓.
Example 4 (work backwards): find the hours
An electrician charges a $85 service fee plus $55 per hour. A customer's bill is $332.50. How many hours did the electrician work?
- Remove the fixed fee: 332.50 - 85 = 247.50 — this is the hourly part.
- Divide by the hourly rate: 247.50 \div 55 = 4.5.
Answer: 4.5 hours (4\tfrac{1}{2} hours)
Check: 85 + 55 \times 4.5 = 85 + 247.50 = 332.50 ✓.
Example 5 (GED-hard): compare two plans
Gym A charges a $40 joining fee plus $25 per month. Gym B charges $32 per month with no joining fee. Over one year (12 months), which gym is cheaper, and by how much?
- Gym A: 40 + 25 \times 12 = 40 + 300 = 340.
- Gym B: 32 \times 12 = 384.
- Compare: 384 - 340 = 44.
Answer: Gym A is cheaper by $44 for the year.
Check: Gym A costs $7 less per month (32 - 25), so over 12 months it saves 7 \times 12 = \$84, but its fee costs $40: 84 - 40 = 44 ✓.
Using the TI-30XS MultiView
- Type a whole step at once to avoid copying errors:
3×1.29+2×3.49enter→ 10.85. The calculator does the multiplications before the addition. - Use parentheses when a step must happen first: (332.50 - 85) \div 55 must be typed
(332.5−85)÷55. Without parentheses you would get 332.50 - 1.545\ldots. - Mixed numbers: use
2ndn/dfor 6\tfrac{3}{4}, or type6.75. Presstoggleto switch a fraction answer to a decimal. - Previous answer: after
enter, pressing an operation key (like×) automatically starts with the last answer, so you can chain steps without retyping. - Rounding: the calculator shows many decimals; you decide whether to round up (whole items to buy), down (complete items you can make) or to the cent.
When NOT to use it: don't let the calculator decide the plan — write the steps first. And estimate before you press enter so a typing slip doesn't go unnoticed.
Common mistakes
- Stopping one step too early. Wrong: the question asks for the change, and you choose the total cost ($21.55). Right: subtract it from the amount paid ($50 − $21.55 = $28.45).
- Using the wrong quantity. Wrong: adding one shirt and one pair of socks when 3 and 2 were bought. Right: multiply each price by its quantity first.
- Treating a fixed fee like a rate. Wrong: hours = \$345 \div \$45. Right: subtract the $75 fee first, then divide: (345 - 75) \div 45 = 6.
- Rounding the wrong way. Wrong: 8.2 boxes → buy 8. Right: you must buy 9 to have enough. Wrong: 6.7 servings → 7 full servings. Right: 6.
- Reading a mixed number as a decimal. Wrong: 6\tfrac{3}{4} = 6.34. Right: 6\tfrac{3}{4} = 6.75.
- Comparing totals instead of unit prices. Wrong: "the $5.76 pack of 24 bottles is cheaper than the $7.92 pack of 36 bottles". Right: compare price per bottle, $0.24 vs $0.22, so the bigger pack is the better buy.
GED test strategy
- Write the plan in words (on your noteboard) before calculating. It keeps multi-step problems organized and makes errors easy to spot.
- Estimate first. Round every number and get a ballpark answer; eliminate choices that are far off.
- Expect "partial" answers among the choices. The GED deliberately includes the answer you would get by stopping one step early (the total instead of the change, one day's pay instead of a week's). Re-read the question before you click.
- Plug the answer back in for work-backwards questions — it is often faster than solving.
- Watch the units in the question and the answer choices (hours vs. minutes, feet vs. square feet, dollars vs. cents).
- Use the formula sheet for total cost and d = rt, and don't overthink: most steps are one of the four operations.
- Pace yourself: multi-step problems can take 2–3 minutes. If you are stuck, flag it and move on.
Check yourself
Luis buys 3 shirts that cost $14.50 each and 2 pairs of socks that cost $4.25 per pair. What is the total cost before tax?
Hint
Find the cost of the shirts and the cost of the socks separately, then add.
Step-by-step solution
- Cost of shirts: 3 \times 14.50 = 43.50.
- Cost of socks: 2 \times 4.25 = 8.50.
- Total: 43.50 + 8.50 = 52.00.
Answer: $52.00
Check: Estimate: 3 \times \$15 = \$45 and 2 \times \$4 = \$8, so about $53 — close to $52.00 ✓.
Tip: Total cost = (number of units) × (price per unit) — this formula is on the GED formula sheet. When a problem has several items, use it once for each item, then add the results.
Check yourself
Keisha earns $15.80 per hour. She works 32 hours each week for 4 weeks. How much does she earn in the 4 weeks, before taxes?
$
Type your answer in the box. Fractions like 3/4 are fine.
Hint
Find the total number of hours first, then multiply by the hourly rate.
Step-by-step solution
- Total hours: 32 \times 4 = 128 hours.
- Pay = hourly rate × hours: 15.80 \times 128.
- 15 \times 128 = 1920 and 0.80 \times 128 = 102.40, so 15.80 \times 128 = 1920 + 102.40 = 2022.40.
Answer: $2,022.40
Check: One week's pay is 15.80 \times 32 = \$505.60, and 4 \times 505.60 = \$2{,}022.40 ✓.
Tip: You can multiply in any order — hours first or one week's pay first. Choose the order that gives easier numbers, and be sure you used every number the question needs (here, the 4 weeks).
Recap
- Use the 4-step plan: understand, plan, solve, check. Label every intermediate result with its unit.
- Translate clue words, but always ask whether you are finding a total or a rate.
- Total cost = units × price per unit, and d = rt, are on the formula sheet; rearrange them by dividing.
- Fixed fee + rate: subtract the fee once before dividing by the rate.
- Round up to buy enough, down for complete items, and money to the cent at the end.
- Work backwards by undoing each step in reverse order; compare options by computing each one fully.