Ah-mien remembers figuring this one out: "Five persimmons weigh 1 jin 2 liang. Ten weigh 2 jin 4 liang. Twenty persimmons weigh 4 and a half jin, and 40 weigh 9 jin.
阿邦仙一邊出題，陳阿勉在心中盤算：五粒一斤二兩，十粒就二斤四兩，二十粒就四斤半，四十粒就九斤。