Complete the following number patterns.
- 621, 553, 485, , 349
- 31, 41, 52, 64, .
- 112, , 132, 139, 144
(a)
621 - 553 = 68
553 - 485 = 68
485 - 68 = 417
Pattern: Keep subtracting 68 from left to right.
(b)
41 - 31 = 10
52 - 41 = 11 (1 is added to 10)
64 - 52 = 12 (1 is added to 11)
12 + 1 = 13
64 + 13 = 77
Pattern: Keep adding 1 to the previous added number from left to right.
(c)
144 - 139 = 5
139 - 132 = 7
132 - 9 = 123
123 - 11 = 112
Pattern: Keep subtracting 2 from the previous subtracted number from right to left.
Answer(s): (a) 417; (b) 77; (c) 123
