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The rule is always 5 and above rounds up.
ROUNDING TO THE NEAREST 10, 100 100 ETC
e.g. 3956.8
To the nearest whole number = 3957
To the nearest 10 = 3960
To the nearest 100 = 4000
T o the nearest 1000 = 4000
DECIMAL PLACES [D.P]
The number of places to round to indicates the number of numbers required after the decimal point. The above rule still applies.
e.g. 59.98327541
To 1 decimal place = 60.0
Notice that the point nought is there because we must have one number after the decimal place even though you should be aware that 60 and 60.0 are the same number
To 2 decimal places the above number = 59.98
SIGNIFICANT FIGURES [S.F]
This generally causes children greater problems as it can work with whole numbers as well as decimals. The above rule of rounding still applies.
- Start from the most significant figure (first none zero number with the greatest place value) and count the required number of figures.
- Look at the next figure to the right of this and if the figure is 5 or more round up, less than 5 leave the number unchanged.
- Add noughts, if necessary, to locate the decimal point and preserve place value.
- When answering a problem remember to include any units and state the degree of approximation used.
e.g.1 4 500 732.0194 to two significant figures becomes 4 500 000
The 4 and 5 were the first two significant figures. The third number is a zero so leaves the 45 unchanged. Zeros are added so that the 4 is still in the millions column.
e.g.2 0.000364907 to 1 significant figure becomes 0.0004
The three is the first significant figure. As the number after the 3 is 6, ie above 5, the 3 is rounded up to 4. The zeros are needed between the decimal point and the 4 in order to preserve place value.