Mental math practice in elementary school is about more than producing a fast answer. Children can split numbers, bridge through ten or use a familiar calculation. These ten original exercises include possible strategies and answers. Choose the ones that match what your child has already learned.
Start with a few calculations
Offer one question at a time and ask, “How could you work it out?” Allow counters, a drawing or a number line when helpful. Moving towards a mental strategy can be gradual; removing a support is not the immediate goal.
The Institute of Education Sciences elementary math intervention guide recommends using clear mathematical language and representations. Our examples below are practice activities, not a standardized assessment or a required grade-by-grade sequence.
Ten mental math exercises with answers
| Calculation | Answer | One strategy to discuss |
|---|---|---|
| 7 + 3 | 10 | Recall the number that completes ten. |
| 8 + 5 | 13 | Add 2 to reach 10, then the remaining 3. |
| 14 − 4 | 10 | Remove the ones. |
| 15 − 7 | 8 | Subtract 5 to reach 10, then another 2. |
| 9 + 9 | 18 | Use a familiar double. |
| 9 + 8 | 17 | Use 9 + 9, then subtract 1. |
| 27 + 10 | 37 | Add one ten. |
| 29 + 6 | 35 | Add 1 to make 30, then add 5. |
| 43 − 9 | 34 | Subtract 10, then add 1 back. |
| 25 + 17 | 42 | Add 10, then 7: 35 + 7. |
These are possible strategies, not the only acceptable methods. For 43 − 9, counting from 34 up to 43 can also check the answer. Listen to your child’s explanation before showing your own.
Look for the step behind an error
If your child answers 33 for 43 − 9, ask them to show an intermediate step. Did they subtract 10 and forget to add 1 back? Revisit that step with objects or a drawing, then try 52 − 9.
Avoid comparing children by speed. Record whether the answer is accurate, whether the explanation makes sense and which support was used. A correct answer reached with counters still tells you something useful about the child’s thinking.
Adjust the numbers, not the pressure
To simplify, stay below ten or practise only combinations that make ten. To extend, try 59 + 6 or 83 − 9 with the same strategy. Ask your child to choose one comfortable question and one they would like to revisit.
Stop when attention fades or errors no longer lead to a useful discussion. Three well-explained calculations can be enough for this activity. For another format, try our dice and card math games. If choosing the operation is the difficult part, use our word problem guide instead.
