50 + 6 = (56)
51 + 6 = (57)
52 + 6 = (58)
53 + 6 = (59)
54 + 6 = (60)
55 + 6 = (61)
           |
  _________|
 |
 V
(56) + 6 = 62
(57) + 6 = 63
(58) + 6 = 64
(59) + 6 = 65
(60) + 6 = 66
(61) + 6 = 67

We just need to keep adding the value 6 to the previous results.