Add and Subtract Mixed Metric Lengths
This Grade 4 Eureka Math skill teaches students to add and subtract mixed metric length measurements by first converting all values to the same smaller unit. For addition, 2 km 300 m + 1 km 800 m converts to 2,300 m + 1,800 m = 4,100 m, which can be written as 4 km 100 m. For subtraction, 5 km 200 m minus 2 km 800 m becomes 5,200 m minus 2,800 m = 2,400 m = 2 km 400 m. This unit-conversion strategy from Chapter 7 of Eureka Math Grade 4 ensures accurate arithmetic with mixed metric lengths.
Key Concepts
To add or subtract lengths with mixed units, first convert all measurements into the common, smaller unit. Then, perform the addition or subtraction with the single unit measurements.
Common Questions
How do you add mixed metric lengths like kilometers and meters?
Convert both measurements to the same smaller unit (meters). Add the results, then convert back to mixed units if needed. For 2 km 300 m + 1 km 800 m: 2,300 + 1,800 = 4,100 m = 4 km 100 m.
How do you subtract mixed metric lengths?
Convert both measurements to meters, subtract, then convert back. For 5 km 200 m minus 2 km 800 m: 5,200 minus 2,800 = 2,400 m = 2 km 400 m.
How do you convert kilometers and meters to just meters?
Multiply the kilometers by 1,000 and add the meters. For 3 km 450 m: (3 times 1,000) + 450 = 3,450 m.
How do you convert meters back to kilometers and meters?
Divide by 1,000 to find whole kilometers; the remainder is the meters. For 4,100 m: 4,100 divided by 1,000 = 4 km with 100 m remainder.
Why must you convert to the same unit before adding or subtracting?
You can only add or subtract like units. Just as you cannot add apples and oranges directly, you cannot add kilometers to meters without a common unit.