3rd Grade Missing Digits Addition Worksheet: Up to 3 Digits

Always begin with the ones column. In a, 6 + 2 = 8, which matches the 8 in the sum, so there is no carry.

In the tens, 5 plus the missing digit must end in 2. Only 7 works, since 5 + 7 = 12. The 1 carries to the hundreds: 4 + 1 + 1 = 6. The sum is 628.

The carry is the key. Each step depends on the one before it.

Let your child try a digit and add the column to see if it fits. Guessing is fine, as long as your child checks each guess.

C is the hardest: _61 + 3_2 = 1,003. The tens need 6 + 4 = 10, and the hundreds need 6 + 3 + 1 = 10. Two carries in a row.

When every blank has a digit, add the whole problem again from the right. Then compare with the key.

Write a sum on paper and cover one digit with a coin. Your child names the hidden digit and explains how they know. Then swap roles.

Notice the reasoning out loud: "You used the carry to find that one."