What is the units digit of the sum of 1! +2! +3! n! when n=2019. include an explanation and what a unit digit is.

Hey!

Finding the factorial for the first few numbers, we have:

1!=1

2!=2

3!=6

4!=24

5!=120

6!=720

7!=720*7

8!=720*56

What we can see as a clear pattern from 5! and on is that our number ends with a 0, making the units digit 0. Therefore, when we add the units digit of 5! and on, we have a result of 0. So, we can simply add the units digits of 1!, 2!, 3!, and 4!, which is 1+2+6+4=13. Since the units digit is the last number, we can drop the tens place to get an answer of 3.

Feel free to ask further questions!

.632

step-by-step explanation:

6 * 1/10 = 3/5

3*0.01 = 0.03

3/5 + 0.03 = .63

2*0.002 = .002

.63 + 0.002 = .632

1/2*qr*rs

step-by-step explanation: