JSS1: MATHEMATICS  1ST TERM

Whole Numbers I  Week 13 Topics1 Quiz

Whole Numbers II  Week 21 Topic1 Quiz

Counting in Base Two  Week 34 Topics1 Quiz

Arithmetic Operations  Week 43 Topics1 Quiz

Lowest Common Multiple (LCM)  Week 52 Topics1 Quiz

Highest Common Factor  Week 61 Topic1 Quiz

Fraction  Week 77 Topics1 Quiz

Basic Operations with Fractions I  Week 83 Topics1 Quiz

Basic Operations with Fractions II  Week 91 Topic1 Quiz

Directed Numbers  Week 103 Topics1 Quiz

Estimation and Approximation I  Week 113 Topics1 Quiz

Estimation and Approximation II  Week 126 Topics1 Quiz
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Decimal Places (d.p)
A number such as 270.8143 is an example of a decimal number.
To find the number of decimal places (d.p) simply count the number of figures after the decimal point. Thus, this number has 4 d.p.
Example:
Find the number of decimal places in the following numbers.
a) 47.04
b) 0.395
Solution:
a) 47.04 > 2 d.p
b) 0.395 > 3 d.p
d.p. means decimal places.
Rounding Off Numbers  Specific Number of Decimal Places:
Sometimes, it is useful to round decimal numbers to a specific number of decimal places or to the nearest whole number.
To round a decimal number to a given number of decimal places:
1. Look for the last digitÂ (i.e. the required decimal place you are rounding to)
2. Then look at the next digit to the right i.e. the decider.
3. If the decider is 5 or more round up (i.e. add 1 to the last digit) if it is less than 5, then add nothing.
Example 1:
Give the number 58.07526 correct to:
a. 1 d.p
b. 3 d.p.
Solution a:
1 d.p  2 d.p  3 d.p  4 d.p  5.dp  
5  8  .  0  7  5  2  6 
The number that represents 1 d.p in this example is 0. The next digit to the right (the decider) is 7 which is greater than 5. So we add 1 to 0 in this example.
i.e. add 1 to the 1st d.p. i.e. 0 + 1 = 1
Therefore, 58.07526 = 58.1 correct to 1 d.p.
Solution b:
1 d.p  2 d.p  3 d.p  4 d.p  5 d.p  
5  8  .  0  7  5  2  6 
The number that represents 3 d.p in this example is 5. The next digit to the right the decider) is 2 which is less than 5. So we add nothing.
Therefore, 58.07526 = 58.075 to 3 d.p
Now try this for yourself
Example 2:
Give the numberÂ 0.0164
Correct to:
a. 2 decimal places
b. 3 decimal places
Solution
a. 0.0164 = 0.02 correct to 2 d.p
b. 0.0164 = 0.016 correct to 3 d.p
Awesome!
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