Multiplying by ten, a hundred or a thousand doesn't need a calculator. It needs one decimal point and the patience to count.
Not started yet.
By the end of this lesson your student should be able to multiply a decimal by 10, 100, 1,000 or any power of ten in his head, by moving the decimal point right as many places as there are zeros, or as the exponent says.
It leans on U1-L9, where the student learned that 10⁵ means five 10s multiplied.
🚨 Moving the point the wrong way. Multiplying by a power of ten always makes the number bigger, so the point always moves right. If the answer got smaller, the point went left.
Running out of digits. 0.34 x 10⁴ needs four moves, and there are only two digits after the point, so two zeros get written in: 3,400.
Write 2.39 on a card and slide a paper decimal point one place right for each row of the table. Moving a real object makes the pattern stick faster than any rule.
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Before You Start
The words this lesson uses. Tap a card to see what it means, then come back to them whenever a question uses one.
Part One
Questions about the story you just read. Pick your answer straight off, or press Find it in the story if you would rather hunt for the sentence first.
Part Two
The word cards are at the top of this page. Look back at them as often as you need, then answer.