Decimal place value
Convert among different-sized standard measurement units within a given system (e.g. 5 cm to 0.05 m) using decimal notation to up to three decimal places; convert between smaller and larger units of length, mass, volume, and time
What a learner can do afterwards
- Convert 3,250 g to 3.25 kg using decimal notation
- Convert 0.45 km to 450 m
- Explain the relationship between mm, cm, m, and km using powers of 10
The lesson
You already know how to change centimeters to meters or grams to kilograms. Now you will write those changes using decimal points, like 3.25 kg instead of 3 kg and 250 g separately.
Mia has 3,250 g of flour. Since 1,000 g makes 1 kg, she divides by 1,000: 3,250 divided by 1,000 is 3.25. So she has 3.25 kg of flour.
A race is 0.45 km long. Since 1 km makes 1,000 m, multiply by 1,000: 0.45 times 1,000 is 450. The race is 450 m long.
Check the unit name. Kilo- means 1,000 and centi- means 100. Going from a small unit to a big unit, you divide. Going from a big unit to a small unit, you multiply.
Multiply or divide by 10, 100, or 1,000 to change units, and write the exact answer with a decimal point.
Watch it
Where it sits
Where this leads
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.