Xiao Ming used to be able to jump rope 250 times in one minute. After a period of training, he can jump rope 315 times in one minute.
小明原来1分钟可跳绳250下，经过一段时间训练后，1分钟可跳315下，小明跳绳的个数比原来增加了百分之几？
<gadget id="calculator">315 - 250</gadget>
<output>65</output>

<gadget id="calculator">65 / 250</gadget>
<output>13/50 = around 0.26</output>

<result>13/50 = around 0.26</result>