Basics
• Decimals are based on the number ten.
• The basic units of the decimal system are 0 1 2 3 4 5 6 7 8 9 10.
• Many arithmetic problems produce an answer in decimal form.
• Zero is often used as a placeholder to the left of the decimal point —> 0.5 = .5
• There is an invisible decimal point to the right of any whole number —> 7. = 7
When asked to convert π, a fraction, or a square root to decimal form, use the toggle button 
.
is the decimal point command.
To convert a decimal to percent, move the decimal point two places to the right; this maneuver is the same as multiplying the decimal by 100.
0.07 → 7.% = 7%
0.07 × 100 = 7%
0.70 → 70.% = 70%
0.70 × 100 = 70%
To convert percent to a decimal, move the invisible decimal point two places to the left; this maneuver is the same as dividing the percent by 100.
0.07 ← 7.% = 7%
7 ÷ 100 = 0.07
0.70 ← 70.% = 70%
70 ÷ 100 = 0.70
The decimal system positions digits as wholes (tens, hundred, thousands, etc.) and parts (tenths, hundredths, thousandths, etc.) of ten.
Positions
2146.8
↑
thousands
2146.87
↑
hundreds
2146.873
”””↑
”””tens
2146.873
””””’↑
””””’ones
2146.873
””””””’↑
””””””’tenths
2146.873
””””””””↑
””””””””hundredths
2146.873
””””””””””↑
””””””””””thousandths
Question
Convert 0.08 to percent.
Answer
8%
Answer Process
To convert a decimal to percent, move the decimal point two places to the right.
0.08 → 8.% = 8%
Question
Convert 0.85 to percent.
Answer
85%
Answer Process
To convert a decimal to percent, move the decimal point two places to the right.
0.85 → 85.% = 85%
Question
Convert 6% to a decimal.
Answer
0.06
Answer Process
To convert percent to a decimal, move the invisible decimal point two places to the left.
0.06 ← 6.% = 6%
Question
Convert 65% to a decimal.
Answer
0.65
Answer Process
To convert percent to a decimal, move the invisible decimal point two places to the left.
0.65 ← 65.% = 65%
Question
What is 6.93 + 0.25?
Answer
7.18
| Input | Display | Comment |
 |
blinker | clears screen |
6  93 + 0 25 |
6.93+0.25 | Addition |
 |
7.18 | Answer |
Decimals |
Question
What is 6.93 – 0.25?
Answer
6.68
| Input | Display | Comment |
|
blinker | clears screen |
| 6 93 – 0 25 |
6.93-0.25 | Subtraction |
|
6.68 | Answer |
Decimals |
Question
What is 6.93 × 0.25?
Answer
1.7325
| Input | Display | Comment |
|
blinker | clears screen |
| 6 93 × 0 25 |
6.93*0.25 | Multiplication |
|
1.7325 | Answer |
Decimals |
Question
What is 6.93 ÷ 0.25?
Answer
27.72
| Input | Display | Comment |
|
blinker | clears screen |
| 6 93 ÷ 0 25 |
6.93÷0.25 | Division |
|
27.72 | Answer |
Decimals |
Question
Round the previous answer to the nearest tenth.
Answer
27.7
Answer Process
See Rounding.
27.72 → 27.7
Practice – Questions
1. Convert 9% to a decimal.
2. Convert 95% to a decimal.
3. Convert 0.04 to percent.
4. Convert 0.45 to percent.
5. Convert 0.455 to percent.
6. What is 3.94 + 0.33?
7. What is 3.94 – 0.33?
8. What is 3.94 × 0.33?
9. What is 3.94 ÷ 0.33?
10. With reference to Question 9, round your answer to the nearest hundredth.
Practice – Answers
1. 0.09
2. 0.95
3. 4%
4. 45%
5. 45.5%
6. 4.27
7. 3.61
8. 1.3002
9. 11.93939394
10. 11.94