### Home > A2C > Chapter 2 > Lesson 2.1.4 > Problem 2-53

2-53.

Notice that all the numbers in (c) are perfect squares.

Notice that 0-18 in (i) are double 0-9 in (c).

Check the sums of pairs of numbers in the sequence.

2-53.

Notice that all the numbers in (c) are perfect squares.

Notice that 0-18 in (i) are double 0-9 in (c).

Check the sums of pairs of numbers in the sequence.