Mastering GED Math: Fractions, Decimals, and Percentages
Hello, future GED graduates! If you could master only ONE topic on the GED Mathematical Reasoning test, this would be it. Fractions, decimals, and percentages (FDP for short) appear in almost every math question. Answer choices deliberately mix the forms â fraction, decimal, percent â to test whether you can glide between them. Discount, tax, tip, and salary word problems? All FDP questions in disguise.
Good news: the TI-30XS calculator is allowed, with special fraction and percent keys. That changes the game. Forget longhand drill-and-kill â the Myanmar classroom way. Success now means: understand what is asked, convert everything into ONE form, estimate first, and let the calculator do the heavy lifting.
Key Concepts & Definitions
Lock in the vocabulary first â half the battle is recognizing what the question describes:
Detailed Explanation & Strategy
1. Converting Fluently: Fractions â Decimals â Percents
The most valuable skill in this lesson. First move on any FDP question: convert everything into ONE form â usually decimals. ž = 3 á 4 = 0.75. Decimal â percent: move the point two places right (0.75 = 75%). Percent â fraction: write over 100 and simplify (75% = âˇâľ/âââ = Âł/â).
Memorize this “magic list” cold â instant recognition saves minutes:
- ½ = 0.5 = 50% | Ÿ = 0.25 = 25% | ž = 0.75 = 75%
- â â 0.333 = 33.3% | â â 0.667 = 66.7%
- â = 0.2 = 20% | â = 0.4 = 40% | â = 0.6 = 60% | â = 0.8 = 80%
- â = 0.125 = 12.5% | â = 0.375 = 37.5% | â = 0.625 = 62.5% | â = 0.875 = 87.5%
See the pattern: fifths build on â = 0.2, eighths on â = 0.125. Only the thirds never terminate.
2. Fraction Operations: Three Rules
Adding/subtracting: you MUST have a common denominator. 1) Find the LCD. 2) Convert each fraction. 3) Add or subtract the numerators only. 4) Simplify. Example: â + â â LCD 6 â â´/â + â = âľ/â.
Multiplying: straight across, then simplify â cancel common factors first (â Ă âš/ââ = Âł/â ). Dividing: invert and multiply: â á â´/â = â Ă âľ/â = âľ/â. Convert mixed numbers to improper fractions first.
3. Percent Problems: “Of”, Change, Reverse
Three buckets. (1) “Percent of”: decimal Ă number (0.15 Ă 200 = 30). (2) Percent change: (change á original) Ă 100% â a $50 bill dropping to $40 is 10 á 50 = 20% decrease. Trap: dividing by the NEW number.
(3) Reverse (finding the original): hardest, hence most tested. A $80 jacket at 25% off â you pay 75%: 0.75 Ă 80 = $60. Backwards: paid $60 after 25% off â original = 60 á 0.75 = $80. Rule: original = sale price á (1 â discount rate).
4. TI-30XS Calculator Strategy
The on-screen TI-30XS is part of the test design â use it. Learn the fraction key (type â directly) and the percent key. Two rules:
- Convert to decimals when comparing or ordering â place value makes “which is largest?” trivial.
- Estimate BEFORE computing â 18% of 492 is “about 100.” Estimation catches wrong-key absurdities.
Comparison: GED FDP Strategy vs Myanmar Classroom Habits
Our schooling trained us for a different test. What must shift:
| Aspect | GED FDP Strategy | Myanmar Classroom Habit |
|---|---|---|
| Calculator use | Expected and provided â part of the test design. | Longhand drills only; calculators often banned. |
| Estimation | Estimate first, then compute â catches errors fast. | Exact-first; answers never sanity-checked. |
| Question context | Word problems rule: discounts, tax, tips, salaries. | Bare-number exercises; word problems cause panic. |
| Answer forms | Choices mix fractions, decimals, percents on purpose. | One form per exercise set; no switching practice. |
| FDP equivalents | Memorized fluency â instant recognition. | Recomputed from scratch every time â too slow. |
Extensive Example Bank (Authentic GED-Style Problems)
Five problems, increasing difficulty. Cover the choices, solve, then check:
Which is the largest?
A. â
B. 0.62
C. 65%
D. â
Solution: C. 65%
What is â â Âź?
A. â
B. âľ/ââ
C. âˇ/ââ
D. âľ/â
Solution: B. âľ/ââ
A bakery makes 240 muffins; 30% are sold by noon. How many were sold?
A. 60
B. 72
C. 80
D. 90
Solution: B. 72
A $80 jacket is 25% off, then 8% tax is added on the discounted price. Final price?
A. $60.00
B. $64.80
C. $65.60
D. $66.40
Solution: B. $64.80
Salary rises from 450,000 to 495,000 kyats. Percent increase?
A. 9%
B. 10%
C. 11%
D. 45%
Solution: B. 10%
Common Mistakes (L1 Interference)
â Wrong: ½ + â = â â Correct: ½ + â = Âł/â + ²/â = âľ/â Why it happens: Fractions get taught as “two stacked numbers.” A fraction is ONE number â add numerators only after denominators match. Check: ½ + â must exceed ½, but â is smaller.
â Wrong: “20% off 150” = 30 (that’s the discount, not the price) â Correct: 20% of 150 = 30; 20% OFF 150 = 120 Why it happens: “Of” and “off” look alike; word-by-word readers blur them. OF = multiply; OFF = subtract. One word flips the answer.
â Wrong: 40% â 50% is “a 10% increase” â Correct: 10 percentage points = a 25% increase (10 á 40) Why it happens: Everyday speech says “10% áááşáááş” for both. The GED is precise: points = subtract; percent change = á original.
â Wrong: 0.5 = 5% â Correct: 0.5 = 50%; 5% = 0.05 Why it happens: Kyat habits make “0.5” feel small. Drill the reflex: decimal â percent moves the point TWO places right, always.
Pro-Tips for High Scorers (College Ready)
GED áááşášááťáŹ: áĄáááŻááşá¸ááááşá¸á áááááááşá¸áážááˇáş ááŹáááŻááşáážáŻááşá¸ááťáŹá¸ (Fractions, Decimals, and Percentages)
áááşášáááŹááŤá GED áááşášááťáŹáážáŹ áá áşááŻáááşá¸áᏠááťá˝ááşá¸ááťááşáááşáááŻáááş ááŽáĄááźáąáŹááşá¸áĄááŹááŤáá˛á áĄáááŻááşá¸ááááşá¸á áááááááşá¸á ááŹáááŻááşáážáŻááşá¸ (FDP) áᏠááąá¸áá˝ááşá¸áááŻááşá¸ááŽá¸ááŤá¸áážáŹ ááŤáááşá áá˝áąá¸á ááŹáá˝áąááᯠááŻáśá áśááąáŹááąá¸ááŹá¸áááş â áĄáááŻááşá¸ááááşá¸á áááá ááŹáááŻááşáážáŻááşá¸á ááŻáśá áśááŻáśá¸ááťááŻá¸ááźáŹá¸ áá°á¸ááźáąáŹááşá¸áááŻááşáááŹá¸ á á áşááťááşááŹááŤá ááťážáąáŹáˇááąá¸á áĄáá˝ááşá áá áŹáááŻá¸ ááźáżááŹáá˝áąááááşá¸ FDP ááᯠáĄááąáŹááşááąáŹááşááŹá¸ááŹááŤáá˛á
ááááşá¸ááąáŹááşá¸á TI-30XS ááááşá¸áá˝ááşá ááş ááŻáśá¸áá˝ááˇáşáááŹááŤá áááşáá˛áˇáĄááźáŹááźáŽá¸áá˝ááşá áᏠááááŻááąáŹáˇáá°á¸á ááąá¸áá˝ááşá¸ááąá¸ááťááşááŹááŹá¸áááşáááŻáˇá ááŻáśá áśáá áşááťááŻá¸áááşá¸ááźáąáŹááşá¸áááŻáˇá áááˇáşáážááşá¸áĄááźáąááźááŻáá˝ááşáááŻáˇá áá˝ááşááťááşáážáŻááᯠá ááşááᯠáá˝ážá˛ááąá¸áááŻáˇááŤáá˛á
áĄááá áááąáŹáááŹá¸ááťáŹá¸áážááˇáş áĄáááášááŤááşáá˝ááˇáşáááŻááťááşááťáŹá¸
ááąáŤááŹááá˝áą áĄáááşáááŻááşááŹáĄáąáŹááşááŻááşááźáááşá
áĄááąá¸á áááş áážááşá¸áááşá¸ááťááşááťáŹá¸
áá ááŻáśá áśááŻáśá¸ááťááŻá¸ áĄááźááşáĄáážááşááźáąáŹááşá¸ááźááşá¸
áĄááąá¸áĄááźáŽá¸ááŻáśá¸ááťá˝ááşá¸ááťááşáážáŻááŤá áĄáŹá¸ááŻáśá¸ááᯠááááĄááźá áş áĄáááşááźáąáŹááşá¸ááŤá ž = 3 á 4 = 0.75á ááá â ááŹáááŻááşáážáŻááşá¸: áĄáážááşáážá áşááąáᏠááŹáá˝ážáąáˇá ááŹáááŻááşáážáŻááşá¸ â áĄáááŻááşá¸ááááşá¸: 100 áĄááąáŤáşááąá¸ááźáŽá¸ áááŻá¸áážááşá¸áĄáąáŹááşááŻááşá
“Magic list” ááᯠáĄáá˝ááşááťááşááŹá¸ááŤá
- ½ = 0.5 = 50% | Ÿ = 0.25 = 25% | ž = 0.75 = 75%
- â â 0.333 = 33.3% | â â 0.667 = 66.7%
- â = 0.2 = 20% | â = 0.4 = 40% | â = 0.6 = 60% | â = 0.8 = 80%
- â = 0.125 = 12.5% | â = 0.375 = 37.5% | â = 0.625 = 62.5% | â = 0.875 = 87.5%
áá áĄáááŻááşá¸ááááşá¸ áá˝ááşááťááşáážáŻ
ááąáŤááşá¸/ááŻááş: á) LCD áážáŹ á) denominator áá°áĄáąáŹááşááźáąáŹááşá¸ á) numerator ááŹááąáŤááşá¸/ááŻááş á) áááŻá¸áážááşá¸áĄáąáŹááşááŻááşá áĽáááŹ: â + â = âľ/âá
ááźážáąáŹááş: áááˇáşáááˇáşááźážáąáŹááşááźáŽá¸ áááŻá¸áážááşá¸áĄáąáŹááşááŻááş (â Ă âš/ââ = Âł/â )á á áŹá¸: ááŻááááá áşááŻááᯠáážááşááźáŽá¸ááźážáąáŹááş (â á â´/â = âľ/â)á
áá ááŹáááŻááşáážáŻááşá¸ááźáżááŹááťáŹá¸
“Percent of”: ááá Ă ááááşá¸ (0.15 Ă 200 = 30)á Percent change: (ááźáąáŹááşá¸áá˛áážáŻ Ăˇ áá°ááááşáááŻá¸) Ă 100%á áááşáááŻá¸áĄáá áşáá˛áˇ á áŹá¸áááᏠáážááˇáşáá˝ááşááŤá
Reverse: $80 áááş 25% ááťážáąáŹáˇáááş 0.75 Ă 80 = $60á ááźáąáŹááşá¸ááźááş: áá°áááąá¸ = 60 á 0.75 = $80á
áá TI-30XS áááşá¸ááťá°ááŹ
áĄáááŻááşá¸ááááşá¸áááŻááşáá˛áˇ ááŹáááŻááşáážáŻááşá¸áááŻááşááᯠááťá˝ááşá¸ááťááşáĄáąáŹááşááŻááşááŤá á) áážááŻááşá¸áážááşáá˛áˇáĄá፠áááááźáąáŹááşá¸ááŤá á) ááá˝ááşáááş áááˇáşáážááşá¸á፠(492 áá˛áˇ 18% â 100)á
áážááŻááşá¸áážááşááťááş áááŹá¸
| áážááŻááşá¸áážááşááťááşááťáŹá¸ | GED FDP áááşá¸ááťá°áᏠ| ááźááşááŹááťáąáŹááşá¸ áĄááąáˇáĄá |
|---|---|---|
| ááááşá¸áá˝ááşá ááş | ááąá¸ááŹá¸áááş â ááŽáááŻááşá¸áá˛áˇáĄá áááşáĄáááŻááşá¸ááŤá | áááşáá˛áˇáá˝ááşáá˛áˇ ááąáˇááťááˇáşáááşá¸áááşáááşá |
| áááˇáşáážááşá¸ááźááşá¸ | áĄáááşáááˇáşáážááşá¸á ááźáŽá¸áážáá˝ááşá | ááááááťááťáĄáááşáá˝ááşá á á áşáááźááˇáşáá°á¸á |
| ááąá¸áá˝ááşá¸ááŻáśá áś | á ááŹá¸ááŻáśá¸ááźáżááŹ: ááťážáąáŹáˇááąá¸á áĄáá˝ááşá áá áŹáááŻá¸á | ááááşá¸ááźáąáŹááşááźáąáŹááşááąáˇááťááˇáşáááşá¸á |
| áĄááźáąááŻáśá áśááťáŹá¸ | ááŻáśá áśááŻáśá¸ááťááŻá¸ ááááşááąáŹááŹá¸áááşá | áá áşá áŻáśáážáŹ ááŻáśá áśáá áşááťááŻá¸áááşá¸á |
| áááşáááŻá¸áá°ááťáŹá¸ | áĄáá˝ááşááťá˝ááşá¸ááťááşáážáŻ: â = 0.625 = 62.5%á | áĄááźáááşáááŻááşá¸ áĄá áááąááźááşáá˝ááş â áážáąá¸áááşá |
ááąáˇááťááˇáşáááş áĽáááŹááťáŹá¸
Which is the largest?
A. â
B. 0.62
C. 65%
D. â
áĄááźáą: C. 65% (áĄááźáąáážááş)
What is â â Âź?
A. â
B. âľ/ââ
C. âˇ/ââ
D. âľ/â
áĄááźáą: B. âľ/ââ (áĄááźáąáážááş)
A bakery makes 240 muffins; 30% are sold by noon. How many were sold?
A. 60
B. 72
C. 80
D. 90
áĄááźáą: B. 72 (áĄááźáąáážááş)
A $80 jacket is 25% off, then 8% tax is added on the discounted price. Final price?
A. $60.00
B. $64.80
C. $65.60
D. $66.40
áĄááźáą: B. $64.80 (áĄááźáąáážááş)
Salary rises from 450,000 to 495,000 kyats. Percent increase?
A. 9%
B. 10%
C. 11%
D. 45%
áĄááźáą: B. 10% (áĄááźáąáážááş)
áĄááźá áşááťáŹá¸ááąáŹ áĄáážáŹá¸ááťáŹá¸ (L1 Interference)
â áážáŹá¸: ½ + â = â â áážááş: ½ + â = Âł/â + ²/â = âľ/â áĄááźáąáŹááşá¸áááşá¸: denominator áá°ááźáŽá¸ááž numerator ááąáŤááşá¸ááŤá ½ + â á ½ áááş ááźáŽá¸ááááşá
â áážáŹá¸: “20% off 150” = 30 â áážááş: 20% of 150 = 30; 20% OFF 150 = 120 áĄááźáąáŹááşá¸áááşá¸: OF = ááźážáąáŹááşá OFF = ááŻááşá á ááŹá¸ááŻáśá¸áá áşááŻáśá¸á áĄááźáąááᯠááźáąáŹááşá¸áááŻááşáááşá
â áážáŹá¸: 40% â 50% á “10% áááŻá¸ááŹáᏔ â áážááş: 10 percentage points = 25% áááŻá¸ááŹááŹá፠áĄááźáąáŹááşá¸áááşá¸: ááŹáááŻááşáážáŻááşá¸áážá áşááŻáá˝áąáˇáááş áááşáá áşááŻááąá¸ááąááŹáᲠáááşá ááşá¸á áŹá¸ááŤá
â áážáŹá¸: 0.5 = 5% â áážááş: 0.5 = 50%; 5% = 0.05 áĄááźáąáŹááşá¸áááşá¸: ááá â ááŹáááŻááşáážáŻááşá¸ áááŻáᏠáĄáážááşáážá áşááąáᏠáĄááźá˛ááŹáá˝ážáąáˇáááŹááŤá
