Written addition
Use the H–T–O model on the right, then write the total here.
H
T
O
0
2
8
+
0
1
7
Start with the ones. Move the ones from both numbers into the O box.
H–T–O place-value model
28 + 17 = ?
Next:Move the ones into O.
First number28
Second number17
Combine here — tap a block, then tap its matching H, T or O box
Blocks show 0. Regrouping changes the form, not the value.
Correct: 0
Attempts: 0
First-try streak: 0
Support: Full