Ray's New Practical Arithmetic · Arts. 56–57 · Unit 6: United States Money
28. Adding and subtracting money
Goal: Your child adds and subtracts dollars, cents and mills, keeping the decimal points in a column.
You'll need
- The book
- A slate, small whiteboard or scrap paper
- A notebook and pencil
What's in the book
Rules and examples for addition and subtraction of United States money, with problems and printed answers.
The lesson, step by step
Warm-up
Mental: $1.50 + $2.25? $5.00 − $1.75? 75 cents + 50 cents?
The rule for adding
Read:
Write the numbers and add as in simple numbers.
Place the decimal point in the sum under the decimal points above.
SayLine up the decimal points first; everything else lines up with them.
Work an example together
Read:
Add together 4 dollars 12 cents 5 mills; 7 dollars 6 cents 2 mills; 20 dollars 43 cents;
Write each as $4.125, $7.062, $20.430 (a zero fills the empty mills place) and the rest of the list, then add.
Subtracting
Read:
Write the numbers and subtract as in Simple Numbers.
Work together:
From $46.28 take $17.75.
(Answer $28.53.)
Independent practice
Your child does the remaining addition problems and subtraction problems.
Check and wrap-up
Answers are printed. Mental: change from a $5 bill for $3.65? ($1.35.)
Tip
Writing a 0 in empty cents or mills places keeps the columns straight. Encourage it.