LENGTH
1. Mistakes when subtracting , adding, multilying or dividing involving conversion of units.
Example :
a) 76.8 m - 51 cm = 25.8 m (wrong because cm was not converted to m )
76.8 m - 51 cm = 76.29 m (correct )
b) 432 m x 16 = 6 912 km ( wrong to change the unit without converting the value )
432 m x 16 = 6.912 km (correct)
MASS
1. Mistakes in calculation involving different units.
Example :
a) 6.87 kg = (6.87 x 100) = 687 g (wrong because 1 kg is not equal to 100 g)
6.87 kg = (6.87 x 1 000 ) = 6 870 g ( correct because 1 kg is equal to 1 000 g )
2. Mistakes when multiplying
Example :
a) 15 kg 781 g X 6 = 90 kg 4 686 g ( wrong because 4 686 g is not converted to kg)
15 kg 781 g X 6 = 94 kg 686 g ( correct because 4000 g is converted to 4 kg)
VOLUME OF LIQUID
1. Did not arrange decimal points in a vertical line.
Example :
a) 9.8 L + 17.4 L + 239.76 L = 1 317.476 L ( wrong because the decimal point are not arranged)
9.80 L + 17.40 L + 239.76 L = 266 . 96 L (correct because decimal point arranged in vertical line)
2. Mistakes when performing operations involving conversions of units.
Example :
a) 280 ml + 13 l + 1 540 ml = 1 833 l (wrong because did not change ml to l )
0.28 l + 13.00 l + 1.54 l = 14.82 l (correct because change ml to l )
Sunday, 11 December 2011
FREQUENTLY MADE MISTAKES TOPIC PERCENTAGE, MONEY, TIME
PERCENTAGE
1. Mistakes made when converting fractions to percentages.
Example : 3/5 = ______ %
3/5 = _____ % 3/5 = ____ %
3/5 = ( 3/5 ) % 3/5 = (3 x 20) / (5 x 20) = 60 / 100
= 0.6 % (wrong) = 60 % (correct)
2. Mistakes made when converting percentages to decimals
Example : Convert 275 % to a decimals.
275 % = 275/100 x 100 275 % = 275/100
= 275 (wrong) = 2.75 (correct)
3. Mistakes in counting percentages
Example : 5 % of 200
5 % of 200 = 5 x 200 5 % of 200 = 5/100 x 200
= 1 000 (wrong) = 10 (correct)
MONEY
1. Mistakes made when adding and subtracting money, decimal point must be arranged in a straight line.
Example : RM 567.20 + RM 12 + RM 4 208 =
2. Mistakes made when performing operations involving brackets. Calculation must be done in brackets first.
Example : RM 7 325.55 x ( 5 + 4 ) =
TIME
1. Mistakes in the units of measurements of time.
Example : 5 hr 42 min + 3 hr 50 min =
5 hr 42 min + 3 hr 50 min = 8 hr 92 min ( wrong ) because 92 min is more than 1 hour
5 hr 42 min + 3 hr 50 min = 9 hr 32 min (correct )
2. Mistakes in calculating the numbers of days between two given dates.
Example : Calculate the number of days between 19 Sept 2008 and 28 Sept 2008
Number of days from 19-28 Sept. 2008
= ( 28 - 19 ) days
= 9 days (wrong)
Number of days from 19-28 Sept. 2008
= ( 28 - 19 + 1 ) days
= 10 days (correct)
( 19 Sept. 2008 is count as 1 day )
1. Mistakes made when converting fractions to percentages.
Example : 3/5 = ______ %
3/5 = _____ % 3/5 = ____ %
3/5 = ( 3/5 ) % 3/5 = (3 x 20) / (5 x 20) = 60 / 100
= 0.6 % (wrong) = 60 % (correct)
2. Mistakes made when converting percentages to decimals
Example : Convert 275 % to a decimals.
275 % = 275/100 x 100 275 % = 275/100
= 275 (wrong) = 2.75 (correct)
3. Mistakes in counting percentages
Example : 5 % of 200
5 % of 200 = 5 x 200 5 % of 200 = 5/100 x 200
= 1 000 (wrong) = 10 (correct)
MONEY
1. Mistakes made when adding and subtracting money, decimal point must be arranged in a straight line.
Example : RM 567.20 + RM 12 + RM 4 208 =
2. Mistakes made when performing operations involving brackets. Calculation must be done in brackets first.
Example : RM 7 325.55 x ( 5 + 4 ) =
TIME
1. Mistakes in the units of measurements of time.
Example : 5 hr 42 min + 3 hr 50 min =
5 hr 42 min + 3 hr 50 min = 8 hr 92 min ( wrong ) because 92 min is more than 1 hour
5 hr 42 min + 3 hr 50 min = 9 hr 32 min (correct )
2. Mistakes in calculating the numbers of days between two given dates.
Example : Calculate the number of days between 19 Sept 2008 and 28 Sept 2008
Number of days from 19-28 Sept. 2008
= ( 28 - 19 ) days
= 9 days (wrong)
Number of days from 19-28 Sept. 2008
= ( 28 - 19 + 1 ) days
= 10 days (correct)
( 19 Sept. 2008 is count as 1 day )
Saturday, 19 November 2011
Kesalahan Matematik Calon UPSR ( whole numbers , fractions , decimals )
FREQUENTLY MADE MISTAKES TOPIC WHOLE NUMBERS
1. Confusion about place value and digit value
Example : State the digit value of 9 in the number 89 143
The digit value of 9 in the number 89 143 is thousands. (wrong)
The digit value of 9 in the number 89 143 is 9 000 (correct)
2. When performing addition, subtraction, multiplication or division in the vertical
form, the numbers must be arranged according to the place value.
Example : 19 850 + 4 678
19 850 1 9 8 5 0
+ 46 78 (wrong) + 4 6 7 8 (correct)
66 630 2 4 5 2 8
3. When performing mixed operations with whole numbers, calculation must be
carried out acording to the general principles.
Example : 4 980 + 1 137 x 60
4 980 + 1 137 x 60 (wrong) 4 980 + 1 137 x 60 (correct)
= 6 117 x 60 = 4 980 + 68 220
= 367 020 = 73 200
FREQUENTLY MADE MISTAKES (FRACTIONS)
1. When converting mixed numbers to improper fractions.
Example : Convert 4 1 to an improper fraction.
7
4 x 7 = 28 (wrong) ( 4 x 7 ) + 1 = 29 (correct)
7 7 7 7
2. When adding and subtract fractions
Example : 1/9 + 5/9 = 6/18 (wrong) 1/9 + 5/9 = 6/9 (correct)
3. When using cancellation method
Example :
1/4 + 4/5 = 1 + 1/5
1/4 + 4/5 = 1 + 1/5
= 1 1/5 (wrong)
1/4 + 4/5 = 5/20+16/20
= 21/20
= 1 1/20 (correct)
FREQUENTLY MADE MISTAKES (DECIMALS)
1. When adding and subtracting decimals,decimal points must be aligned in a straight line.
Example : 289 . 14 + 15 . 3 =
2 8 9 .1 4 2 8 9 . 1 4
+ 1 5 .3 + 1 5 . 3
2 9 0 6 . 7 (wrong) 3 0 4 . 4 4 (correct)
2. When multiply and divide decimals,decimal point must be aligned in straight line.
Example : 6 8 5 x 0.7
6 8 5 6 8 5
x 0 . 7 x 0. 7
4 7 9 5 (wrong) 4 7 9 . 5 (correct)
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