Academic Session 2020 - PDF document

Academic Session 2020 MATHEMATICS Class III TOPICMEASUREMENT(MEASUREMENT OF LENGTH) MEASUREMENT OF LENGTH Length is a measure of how long something is. We use rulers or tape to measure length. We most

of the time measure length in millimeters, centimeters (cm), meters (m) and kilometers (km) as unit of length. Millimeters and centimeters are used to measureshort lengths . • Long lengths are m

easured in meters. • Thedistance between two far off places is measured in kilometers (km) • Example:The length of a pencil is measured in centimeters, Length of bed in meters, while the dis

tance between two places is measured in kilometers. OBJECTS MEASURED IN CENTIMETRESPENCIL PENCILBOX MOBILE PHONEERASER CHALK BOX OBJECTS MEASURED IN METRESBUNDLE OF

CLOTHHEIGHT OF BUILDINGBLACKBOARD OBJECTS MEASURED IN KILOMETRESLENGTH OF A RIVERLONG DISTANCE The standard unit of length is ‘Metre’. 1 m = 100 cm or 100 cm = 1 m1 km = 1000 m or 1000 m = 1

kmConversions:To convert metresinto centimetres, we multiply the given number of metresby 100.Example 1:Convert 5m into cm5m = 5 x 100= 500cmExample 2:Convert 4m 85cm into cm4m 85cm = 4 x 100cm + 85cm=

400cm + 85 cm = 485 cm Q1)Convert metresinto centimetresmetre= 100 centimetre1m = 100 cm6m = 6 X 100= 600cm7m= 7 X 100 = 700cm10m= 10 X 100 = 1,000cm5m46cm= 5 X 100cm + 46cm= 500cm + 46cm= 546cm e) 8m

7cm= 8 X 100cm + 7cm= 800 cm + 7 cm= 807 cmf) 9m 60cm= 9 X 100cm + 60 cm= 900cm + 60cm= 960 cm To convert kilometers into meters, we multiply the given number of kilometers by 1000.Example 1:Convert 15

km into m15m = 15 x 1000= 15000mExample 2:Convert 4km 850m into m4km 850m =4 x 1000m + 850m= 4000m + 850m= 4850m Q) Convert Kilometresinto metresKilometre= 1000 metre1 Km = 1000ma) 5km= 5 X 1000= 5,00

0mb) 7km= 7 X 1000 = 7,000mc) 10km= 10 X 1000 = 10,000 md) 7km658m= 7 X 1000m + 658m= 7000m + 658m= 7658m e) 9km45m= 9 X 1000m + 45m= 9000m + 45m= 9045mf) 6km7m= 6 X 1000m + 7m= 6000m + 7m= 6007m CONVE

RSION OF CENTIMETRES INTO METRESWe know that 100 cm = 1 m.To convert centimetresinto metresdividethe centimetresThequotientis the metresand theremaindergives the centimetresExamplesConvert 500 cm into

m.Divide 500 by 100,500 cm 100 = 5Quotient = 5, Remainder = 0So, 500 cm = 5 mConvert 5275 cm into m.On dividing 5275 by 100, we getQuotient = 52, Remainder = 75So, 5275 cm = 52 m 75 cm Other method: 52

75 cm = 5200 cm + 75 cmWe know that 5200 cm = 52 mSo, 5275 cm = 52 m + 75 cm = 52 m 75 cm Q) Convert centimetresinto metres1m= 100cm100cm= 1m900cm= 900100= 9m1000cm= 1000100 = 10m4589cm= 45m89cm7805cm=

78m5cm 3460cm= 34m60cm CONVERSION OF METRES INTO KILOMETRESWe know that 1000 m = 1 km.To convert metresinto kilometres, divide the metresby 1000.Thequotientis the kilometresand theremaindergives the m

etresExamplesConvert 6000 m into km.Divide 6000 by 1000,6000 m 1000 = 6Quotient = 6, Remainder = 0So, 6000 m = 6 kmConvert 7275 m into km.On dividing 7275 by 1000, we getQuotient = 7, Remainder = 275So

, 7275 m = 7 km 275 m Other method: 7275 m = 7000 m + 275 mWe know that 7000 m = 7 kmSo, 7275 cm = 7 km + 275 m = 7 km 275 m Q)Convert metresonto kilometres1km= 1000m1000m= 1kma)5000m= 5kmb) 7000m= 7km

c) 10,000m= 10kmd) 4689m= 4km689me) 20754m= 20km754mf) 32006m= 32km6m EXERCISE Q) Fill in the blanks8m= ______cm16m= ______cm40km= _______m3m58cm= ______cm5km426m= _______m2749m= _____km ____m4274cm=

______m _____cm ANSWER KEY Q) Fill in the blanks 8m= __800____ cm b) 16m= __1600_ ___cm c) 40km= ___40,000 ____m d) 3m58cm= __ ___cm e) 5km426m= __5426_____ m f) 2749m= __ ___km __749 __m g) 4274cm= _