Adding and Subtracting to Four Digits

On this Quest, you'll discover…

Calculate with whole numbers of at least four digits and check your work.

• Estimate a sum or a difference by rounding off before calculating.
• Add and subtract whole numbers of at least four digits by building up and breaking down numbers.
• Use a number line, and rounding off and compensating, as other calculation techniques.
• Use addition and subtraction as inverse operations to check a written or mental calculation.
• Compare two techniques on the same calculation and explain which one was more efficient and why.