Idea 11of 24Builds onTimes 0.01 is one hundredth
Times 0.1 makes a number smaller
Can multiplying make a number smaller?
Today you'll discover
- why × 0.1 gives less
- what the decimal point does
- how to check the size
Think first70 times 0.1
Is 70 × 0.1 bigger or smaller than 70?
Decide first, then press Next. Watch the dot between the ones and the tenths.
A place-value chart with 70 in the top row. Arrows take each digit one column right; the bottom row fills with 7.0, the 0 faded, and the decimal point sits in the same place in both rows. Then 70 × 0.1 = 7, smaller than 70. The last step shows 120 × 0.01.
See the whole ideathe big idea and the key word, in one place
The big idea
Times 0.1 or 0.01 makes a number smaller: the digits move, the point stays.
Easy to get wrong“Multiplying makes it bigger” is only true when you multiply by more than 1. Times 0.1 takes a part.
Ten percent off0.1 of a $70 jacket's price is $7: one tenth of the price.
Key word
- decimal point
- the dot between the ones and the tenths; it stays put while the digits move
Ready to use it?
- Say whether a product will be bigger or smaller.
- Multiply by 0.1 or 0.01 and check the size.