A natural number minus 45 and plus 44 is still a perfect square number. What is this number?
一个自然数减去45及加上44都仍是完全平方数，此数为多少．
<gadget id="calculator">45 ** 2</gadget>
<output>2_025</output>

<gadget id="calculator">2_025 - 44</gadget>
<output>1_981</output>

<result>1_981</result>