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1st Grade Math
12. 1.NBT.C.4
12.12 Completing addition statements up to 100
Completing Addition Statements up to 100
Learn to find missing numbers and missing digits in addition statements up to 100 using subtraction, counting on, and place value thinking.
What You'll Learn
Recognize that a missing addend can be found because addition and subtraction undo each other.
Apply the rule that if \( a + b = c \), then the missing number satisfies \( b = c - a \).
Count on from the known number to the total to find a missing addend up to 100.
Break two-digit numbers into tens and ones to find a missing digit inside an addition statement.
Check every completed statement by adding the numbers back together to confirm the total.
What You'll Practice
1
Finding missing first addends when given the second addend and sum
2
Finding missing second addends when given the first addend and sum
3
Solving addition equations with sums up to 100
Why This Matters
Completing addition statements builds your number sense and problem-solving skills. This foundational skill prepares you for algebra, where you'll solve equations with unknowns, and helps you think flexibly about numbers in everyday situations like calculating change or missing quantities.
This Unit Includes
1 Video lesson
Practice exercises
Learning resources
Skills
Addition
Missing Addends
Number Sense
Inverse Operations
Equations
Place Value
OH Curriculum Aligned