How do you spot a fraction?
Last updated: 2 Mar 2010
In the GMAT fractions are often disguised as percentages or decimals.
We have already seen that 0.125 is equal to 1/8. How did we know that?
The easiest way to have these fractions at your fingertips is to memorize them.
Fractions, percentages and decimals
This table shows the most commonly used fractions (in the GMAT) and their decimal and percent equivalents.
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.333... | 33 1/3% |
| 2/3 | 0.666... | 66 2/3% |
You will notice that one third is written 0.333... , that is to say the 3 repeats an infinite number of times. This is one of the other advantages of fractions, some numbers cannot be written down in decimal form.
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/4 | 0.25 | 25% |
| 3/4 | 0.75 | 75% |
Why didn't we include 2/4 ?
Because we have already included it in the table. 2/4 = 1/2
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/5 | 0.2 | 20% |
| 2/5 | 0.4 | 40% |
Followed by 60% and 80%.
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/6 | 0.1666... | 16 2/3% |
| 5/6 | 0.8333... | 83 1/3% |
You should be able to see why 2/6, 3/6 and 4/6 have not been included.
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/8 | 0.125 | 12.5% |
| 3/8 | 0.375 | 37.5% |
| 5/8 | 0.625 | 62.5% |
| 7/8 | 0.875 | 87.5% |
| 1/9 | 0.111... | approximately 11% |
| 2/9 | 0.222... | approximately 22% |
A clear pattern emerges from 1/9, 2/9...
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/10 | 0.1 | 10% |
| 1/20 | 0.05 | 5% |
| 1/100 | 0.01 | 1% |
Do you think you can remember all that?
Take your time to review the fractions above and then see if you can do the exercise on the next page.
Hi
1/3 0.333... 33%
2/3 0.666... 66%
Is there a reason why this is not:
1/3 0.333... 33 1/3%
2/3 0.666... 66 2/3%
?
Same applies to the x/9 fractions
how do you convert 3/8, 5/8, 7/8, 2/5, 5/6 to decimals and percentages?
gmat_generic, you're right 1/3 and 2/3 are 33 1/3% and 66 2/3% respectively. The ninths are never needed precisely but are useful to know approximately.
ashionhodges, the fastest way (and speed is important in the GMAT) is simply to learn them so that you can reel off all the common conversions in the table above.