Adding and Subtracting Meters and Centimeters 3 B

Adding and Subtracting Meters and Centimeters 3 B: 6. 1 c

Adding m & cm with no renaming 2 m _____ 85 cm m 60 cm + 25 cm = _____ How do you get the answer? Since there are no meters in front of 25 cm, just add the centimeters. 2

Adding m & cm with renaming 3 m _____ 35 cm m 60 cm + 75 cm = _____ You can still add the centimeters since there are no meters in front of the 75 cm. 60 cm + 75 cm = 135 cm Can you leave the 135 cm as it is? Convert it into m and cm. 1 m 35 cm + 75 cm 2 m 135 cm = 2 m 60 cm 2 3 m 35 cm

Another way You could also make 100 with either 60 cm or 75 cm. 2 m 60 cm 35 cm 2 m 35 cm + 75 cm 25 cm + 1 m = 3 m 35 cm

Another way Now let’s make 100 with the 60. How much do we need from the 75? How much is left? 2 m 60 cm + 75 cm 40 cm 2 m + 1 m 35 cm = 35 cm 3 m 35 cm

One more strategy… You can add the numbers up vertically. First, convert into cm. Add. Convert back to m and cm. 2 m 60 cm + 75 cm 3 m 35 cm + 260 cm 75 cm 335 cm

Adding both meters and centimeters 2 m 65 cm + 3 m 20 cm = _____ m _____cm Use mental calculation to add the meters. Then add the centimeters. 2 m 65 cm + 3 m 20 cm 5 m 65 cm + 20 cm 5 m 85 cm

Adding both meters and centimeters Try this one… 2 m 65 cm + 3 m 40 cm = _____ m _____cm Add the meters. Then add the centimeters and rename. 2 m 65 cm + 3 m 40 cm 5 m 65 cm + 40 cm 5 m 105 cm 6 m 5 cm

Use vertical adding, if you prefer First, convert into cm. Add. Convert back to m and cm. 2 m 65 cm +3 m 40 cm 6 m 5 cm + 265 cm 340 cm 605 cm

Subtracting both meters and centimeters 5 _____ 5 cm m 30 cm – 25 cm = _____m To find the answer, subtract 25 cm from 30 cm. There are no meters to take away so the 5 m stays the same. 5

Subtracting both meters and centimeters 4 _____ 55 cm m 30 cm – 75 cm = _____m Take 100 cm from the 5 meters. What’s left? Subtract the 75 from the 100. Add the remaining cm together. 5 5 m 30 cm 4 m 30 cm – 75 cm = 100 cm – 75 cm = 4 m 30 cm + 25 cm = 4 m 55 cm

Other strategies Is there another way to solve the problem 5 m 30 cm – 75 cm? You can rename 5 m 30 cm. Then subtract. 5 m 30 cm – 75 cm = 4 m 130 cm – 75 cm = 4 m 55 cm

Use vertical subtracting, if you prefer First, convert into cm. Subtract. Convert back to m and cm. 5 m 30 cm – 75 cm 4 m 55 cm – 530 cm 75 cm 455 cm

Subtracting when you don’t have to rename 5 m 30 cm – 2 m 25 cm = ____ m _____ cm How should we solve this? Subtract meters first. Then subtract centimeters. 5 m 30 cm – 2 m 3 m 30 cm – 25 cm 3 m 5 cm

How do we find the difference between 5 m 30 cm and 2 m 75 cm? Let’s look at three subtraction strategies… RENAME CONVERT 5 m 30 cm – 2 m 75 cm = 3 m 30 cm – 2 m 130 cm – 5 m 30 cm – 2 m 75 cm = 2 m 55 cm 75 cm = 530 cm – 275 cm 255 cm 2 m 55 cm MAKE 100 5 m 30 cm 3 m 30 cm 2 m 30 cm – – 2 m 75 cm = 100 cm – 75 cm = 2 m 30 cm + 25 cm = 2 m 55 cm

Now you try. Textbook page 12 Tasks 14 -15 14 a) 5 m 25 cm b) 1 m 55 cm 15 a) 9 m 32 cm b) 3 m 79 cm c) 8 m 30 cmd) 6 m 46 cm e) 3 m 20 cmf) 9 m 1 cm g) 6 m 15 cmh) 5 m 24 cm i) 4 m 55 cm j) 3 m 95 cm k) 3 m 55 cml) 2 m 30 cm

Extra practice and/or Homework WB pages 9 -10 EP 113 -114 Review 1 B