It takes 4 sticks to place a square "□", 7 sticks to place two squares in a row, 10 sticks to place 3 squares in a row, how many sticks are needed to place 15 squares in a row.
摆一个正方形"□"要用4根小棒，连摆两个正方形要7根小棒，连摆3个正方形要10根小棒，那么连摆15个正方形要多少根小棒．
<gadget id="calculator">3 * 15</gadget>
<output>45</output>

<gadget id="calculator">45 + 1</gadget>
<output>46</output>

<result>46</result>