LEARN · PRACTISE · DISCOVER

Add Mentally with Flexible Strategies

Read at your own pace. Try the practice, then continue your course.

Add numbers mentally by splitting them, making a ten, or adjusting to a nearby friendly number.

This lesson is for members

Join to unlock this lesson and the full course library, or log in if you are already a member.

THE CURIOSI · EXPLORE & TRY

Explore the model, then test your understanding. Select each numbered stop to discover its role.

Strategy model: follow the labelled quantities and explain each change. Number-line jumps are schematic.

1Start at thirty-eight

The calculation is 38 + 7.

2Use two of the seven

Split 7 into 2 and 5. Adding 2 reaches 40.

3Add the remaining five

40 + 5 = 45. Both jumps together add exactly 7.

Choose a strategy you can explain. Check the numbers and include units where needed.

Choose one answer for each question, then check. Practice results stay on this page and do not change course completion.

1. 38 + 7 equals… 47 43 45

2. For 49 + 28, you calculate 50 + 28 = 78. What next? Subtract 10 Subtract 1 Add 1

3. Which inverse check supports 39 + 26 = 65? 65 − 26 = 39 65 + 26 = 39 39 − 26 = 65

Read the answer explanations

Focus on understanding before speed. Use paper, counters or a spoken explanation whenever they help you keep track.