Jeremy is writing down a sequence of integers. He writes 1 as his first number. Then, he
squares it and adds 3, writing down 4 next. He squares 4 and adds 3, writing down 19 as his third
number. If Jeremy continues his square-and-add pattern, what will the units digit of the 20th
number in his list be?

4 is the unit's digit of the 20th number.

Step-by-step explanation:

Let us try to find out a pattern for the unit's digit of the terms.

1st term is 1, so unit's digit of 1st term is 1.

2nd term so unit's digit is 4.

3rd term so unit's digit is 9.

4th term so unit's digit is 4.

5th term's unit digit: Square of unit's digit of 4th term + 3

i.e. 9.

:

We can see that the pattern is

3rd, 5th, 7th ...... terms have 9 as the unit's digit.

2nd, 4th, 6th.... terms have 4 as the unit's digit.

So, 20th term will have 4 as the unit's digit.

14

step-by-step explanation: