Xiaodong and grandma go upstairs, Xiaodong walks fast, grandma walks slowly, when Xiaodong reaches the 3rd floor, grandma only goes up to the 1st floor, then when Xiaodong reaches the 10th floor, how many floors does grandma go up to?
小东与奶奶上楼，小东走得快，奶奶走得慢，小东上了3层时，奶奶才上1层，那么当小东到10楼时，奶奶上到多少楼．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>