Ray's New Practical Arithmetic · Art. 20 · Unit 2: Addition
10. Adding two columns at once
Goal: Your child adds two-figure numbers in one step to speed up column addition.
You'll need
- The book
- A slate, small whiteboard or scrap paper
- A notebook and pencil
What's in the book
A method for adding two columns at a time, followed by a page of column examples.
The lesson, step by step
Warm-up
Mental: 47 + 30? 77 + 6? 83 + 40? 123 + 9?
The idea
Read:
An excellent practice, in order to secure readiness and accuracy, is to add two columns at once.
SayInstead of adding units and then tens, we add whole two-figure numbers: first the tens, then the units.
Work the book example
Follow the book's worked example:
Beginning with 47, add the 3 tens above, which equal 77.
Keep going up the column the same way: add tens, then units, saying only the running totals.
Guided practice
Do the first example on the page together, saying the running totals aloud.
Independent practice
Your child does three or four more of the examples on the page.
Check
Answers are printed under many of the examples. For any without a clear answer, check by adding one column at a time.
Wrap-up
Mental: 56 + 27? (83.) 64 + 38? (102.)
Tip
This is a skill for speed. If it frustrates your child, go back to one column at a time and return to this later.