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Scholastic
Scholastic: Study Jams! Math: Addition and Subtraction: Estimate Sum, Difference
Complete this step by step lesson to estimate the sum and difference then test yourself.
CK-12 Foundation
Ck 12: Arithmetic: Estimation of Whole Number
[Free Registration/Login may be required to access all resource tools.] Round whole numbers in order to estimate sums and differences.
CK-12 Foundation
Ck 12: Arithmetic: Estimation of Whole Number
[Free Registration/Login may be required to access all resource tools.] Round whole numbers in order to estimate sums and differences.
CK-12 Foundation
Ck 12: Arithmetic: Decimal Subtraction
[Free Registration/Login may be required to access all resource tools.] Subtracting decimals with and without rounding