2.1.2.4
Use mental strategies and algorithms based on knowledge of place value and equality to add and subtract two-digit numbers. Strategies may include decomposition, expanded notation, and partial sums and differences.
Khan Academy ResourcesSubtract within 100 using place value blocksAdd within 100 using place value blocksAdd within 100 using a number line2-step subtraction word problems within 100Find the missing number (add and subtract within 100)Adding up to four 2-digit numbers word problemsAdding up to four 2-digit numbersAdd using groups of 10 and 100Select strategies for adding within 100Break apart 2-digit addition problemsSubtract within 100 using a number lineAdd 2-digit numbers by making tensAddition word problems within 100Adding by making a group of 10Missing numbers in addition and subtractionAddition and subtraction with number linesAdding 2-digit numbers without regroupingAdding multiple 2-digit numbers word problemsSubtracting 1s using place valueSubtracting a 1-digit number with regroupingAddition word problem: horsesSubtracting 10s using place valueUnderstanding place value when adding onesStrategies for adding 2-digit numbersSubtracting two-digit numbers without regroupingAdding with regroupingUnderstanding place value when adding tensBreaking apart 2-digit addition problemsAdding four two digit numbersAdding 53+17 by making a group of 10
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