The sum of the three natural numbers A, B, and C is 100. When dividing A by B, or dividing C by A, the result is a quotient of 5 with a remainder of 1. What is A's number?
甲、乙、丙三个自然数的和是100，甲数除以乙数，或丙数除以甲数，得数都是商5余1，问甲数是多少．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">15 + 1</gadget>
<output>16</output>

<result>16</result>