PLACE- VALUE INTERPRETATION Students consider
the place value of digits and what that means
when adding or subtracting numbers.
Zeke buys cider for $1.97 and donuts for $0.89.
The clerk said
the bill was $10.87. What did the clerk do wrong?
The cider is and the donuts are
So the cost is In 1.97 + 0.89, we
hundredths to hundredths tenths to
and ones to ones
clerk incorrectly added dollars and pennies (ones and
tenths, tenths and hundredths).
DECIMALS AS FRACTIONS Write decimals as
fractions, multiply, write the answer as a
decimal, and relate the number of decimal
places in the factors to the answer .
PLACE-VALUE INTERPRETATION Students see
why counting decimal points make sense and
use the short-cut algorithm: multiply the
decimals as whole numbers and adjust the
place of the decimal in the product.