the digital sum of a number is the sum of its digits. for how many of the positive integers 24 - 140 inclusive is the digital sum a multiple of 7?  Pick:
A) 7 B) 8 C) 14 D) 15 E) 20
<gadget id="calculator">24 - 7</gadget>
<output>17</output>

<gadget id="calculator">17 - 2</gadget>
<output>15</output>

<result>D</result>
the digital sum of a number is the sum of its digits. for how many of the positive integers 24 - 140 inclusive is the digital sum a multiple of 7?
subtract(subtract(24, 7), const_2)
is there other way than just listing ? 25 34 43 52 59 61 68 70 77 86 95 106 115 124 133 15 ways . . d