Math Background

Addition and Subtraction: Tips and Tricks

  • Encourage the use of grid paper to properly align digits in addition and subtraction problems. It is a useful aid for those students having difficulty keeping digits in proper columns.
  • If students are experiencing errors in addition or subtraction, have them write the problems in place-value charts. Writing the digits in the chart will help align columns for easier computation.
  • Urge students to check their answers by using the inverse operation. This not only reinforces use of another operation, but also provides additional practice in number facts.
  • If students are forgetting to add the regrouped digit to the next column, have them write the digit lightly above the correct place. It may be necessary to circle this digit so that it is not forgotten.
  • Have students find the total number of pages in one mathematics and in one science textbook. Encourage some students to model the problem using place-value charts and blocks. Emphasize regrouping as it is needed.
  • Once students have grasped the concept of regrouping, introduce money amounts greater than 99 cents, using decimal notation.
  • Have students orally explain how adding and subtracting money is similar to adding and subtracting 3-digit numbers.
  • Set up a grocery store in the classroom by using empty boxes of foodstuff. Write a price on each box, and allow students to “shop.” Have them take turns being the clerk who finds the total of the purchases.

Houghton Mifflin Math Grade 3