The decimal place of the first multiplier is 1, the decimal place of the second multiplier is 2, what is the number of decimal places of the product.
第一个乘数的小数位数是1，第二个乘数的小数位数是2，积的小数位数是多少．
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<result>3</result>