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Mental Addition
Select the skills to practice, and then click Go!
Foundational Skills
Larger + Smaller (within 10)
\[ 7 + 2 = ? \]
Larger number first.
Smaller + Larger (within 10)
\[ 2 + 7 = ? \]
Smaller number first.
Doubles within 10
\[ 4 + 4 = ? \]
Identical single digits.
Near doubles within 10
\[ 4 + 5 = ? \]
Differ by 1 or 2.
Adding within 20
Bridging 10
\[ 7 + 5 = ? \]
Answer between 11 and 18.
Single + Teen (No Bridge)
\[ 14 + 3 = ? \]
Stays below 20.
Single + Teen (Bridging 20)
\[ 16 + 5 = ? \]
Answer 20 or more.
Doubles of teens
\[ 14 + 14 = ? \]
Identical teen numbers.
Near doubles within 20
\[ 7 + 8 = ? \]
Differ by 1 or 2.
Adding with two-digit numbers
Single + 2-digit (No Bridge)
\[ 34 + 5 = ? \]
Don’t cross the ten.
Single + 2-digit (Bridge)
\[ 37 + 6 = ? \]
Cross into next ten.
Near doubles (2-digit)
\[ 24 + 25 = ? \]
Differ by 1 or 2.
Adding multiples of 10
Multiples of 10 (< 100)
\[ 30 + 40 = ? \]
Answer 100 or less.
Multiples of 10 (> 100)
\[ 60 + 50 = ? \]
Answer over 100.
Mult 10 + 2-digit (< 100)
\[ 34 + 20 = ? \]
Not bridging 100.
Mult 10 + 2-digit (> 100)
\[ 67 + 50 = ? \]
Bridging 100.
Compensation Strategies
Add 9 to single digit
\[ 6 + 9 = ? \]
Add 10, subtract 1.
Add 8 to single digit
\[ 7 + 8 = ? \]
Add 10, subtract 2.
Add 9 to 2-digit
\[ 45 + 9 = ? \]
Add 10, subtract 1.
Add 19 to 2-digit
\[ 34 + 19 = ? \]
Add 20, subtract 1.
Add 98 to 3-digit
\[ 356 + 98 = ? \]
Add 100, subtract 2.
Adding 3-digit numbers
Two multiples of 100
\[ 300 + 500 = ? \]
Simple hundreds.
3-digit multiples of 10
\[ 320 + 450 = ? \]
Ends in 0.
Single + 3-digit (Tens)
\[ 234 + 8 = ? \]
Bridge tens only.
Single + 3-digit (All)
\[ 294 + 8 = ? \]
Bridge tens and hundreds.
Timer (Optional)
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Question