Question 1
Find the missing number.
a) 21, 27, 33, 39, ( ), 51, ( ), ...
b) 0, 3, 9, 18, 30, ( ), 63, ...
c) 1, 4, 9, ( ), 25, ( ), ...
d) 2, 6, 12, ( ), ( ), ...
e) 11, 88, 16, 80, 21, 72, ( ), ( ), ...
**Editorial note for this self-study exercise:** Use these intended pattern families throughout: (a) constant first difference; (b) first differences increasing by a constant amount; (c) consecutive positive-integer squares; (d) products of consecutive positive integers; (e) separate arithmetic patterns in the odd and even positions. Enter all nine missing integers in part order (a) to (e), left to right within each part, separated by semicolons with no spaces.
a) 21, 27, 33, 39, ( ), 51, ( ), ...
b) 0, 3, 9, 18, 30, ( ), 63, ...
c) 1, 4, 9, ( ), 25, ( ), ...
d) 2, 6, 12, ( ), ( ), ...
e) 11, 88, 16, 80, 21, 72, ( ), ( ), ...
**Editorial note for this self-study exercise:** Use these intended pattern families throughout: (a) constant first difference; (b) first differences increasing by a constant amount; (c) consecutive positive-integer squares; (d) products of consecutive positive integers; (e) separate arithmetic patterns in the odd and even positions. Enter all nine missing integers in part order (a) to (e), left to right within each part, separated by semicolons with no spaces.